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I 



MORTAES, PLASTERS, STUCCOS 

Artificial Marbles, Concretes, Portland 
Cements and Compositions 



BEING A 

Thorough and Practical Treatise 

ON THB 

LATEST AND MOST IMPROVED METHODS OF PREPARING 

AND USING LIMES, MORTARS, CEMENTS, MASTICS AND 

COMPOSITIONS IN CONSTRUCTIVE AND DECORATIVE 

WORK, INCLUDING A PRACTICAL TREATISE ON 

REINFORCED CONCRETES 



Prepared, Compiled and Edited By 
FRED T. HODGSON, 0. A. A. 

AUTHOR OF 

'Treatise on Uses of The Steel Square," "Modern Carpentry," 

"Architectural Drawing Self-Taught," "Up-to-Date Hardwood 

Finisher," "20th Century Bricklayer," "Modern 

Estimator," "Art of Wood-Carving," Etc. 



PROFUSEL.Y IliEUSTRATED 

With Working Drawings and Sketches of Tools, 
^ Appliances, Ceiling Designs and Examples 
of Ornamental Stucco Work 




CHICAGO 
FREDERICK J. DRAKE & CO., PUBLISHERS 






Copyright, 1906, 
by 
FREDERICK J. DRAKE & CO. 



Copyright, 1914, 

by 

FREDERICK J. DRAKE & CO. 



< t 
• , r 



APR 29 1914 



/. 




CI.A371641 



PREFACE 



In introducing this book to American Builders and 
others who are interested in the use of plasters, stuccos, 
cements and mortar, I feel that I am doing them a 
service, as there is no such work, so far as I have been 
able to discover, published in this country that appeals 
so directly to the practical workman as the present vol- 
ume does ; as I have endeavored to put together as much 
practical stuff as it was possible to wedge in in a vol- 
ume of this size, and in order to do this, I have gleaned 
the best things I could find in English, American and 
other books and journals, to which I have added much 
drawn from my own experience, and from the experi- 
ences of many practical workmen. I have particularly 
drawn at length from Miller's exhaustive work on the 
subject of plastering and stucco work, and am also 
indebted to the same source for a number of illustra- 
tions used in PART ONE. I have also drawn from 
Robert Scott Burns to some small extent, and from an 
earlier work of my own, and from articles I have fur- 
nished to various building journals during the last 
thirty years. Part Two is made up partly from my 
own experience, and partly from treatises on cements 
and concretes, and from Government Bulletins pub- 
lished in Washington, D. C. The paragraphs and illus- 
trations on reinforced concrete are mostly taken from 
reports of scientific societies, and from papers read 
before conventions, and from letters and descriptions 
prepared by manufacturers and users of Portland ce- 

5 



6 CEMENTS AND CONCRETES 

ment, fupnished me on application, and from materials 
gathered from many sources, and, while I have added 
considerable from my o^vn knowledge of the sabject, 
it may be said that the work is almost a compilation 
taken from the best authorities on the subjects dis- 
cussed. 

There is enough material on the subject of concrete 
floating about in the technical press, of the best kind, 
to build up three or four volumes of the size of this 
one, but, in analyzing it, I have sifted it down to the 
limits of this book, preserving that, which in my judg- 
ment, was best for the practical worker, and leaving out 
the most of that which might be termed theoretical and, 
therefore, to a large extent unfit for artisans' purposes. 
In making the selections in matters of this kind, the 
personal factor must necessarily be of more or less 
value, and I flatter mvself that, after a successful build- 

7 t/ 7 

ing experience in various forms, covering a period of 
over fifty years, my knowledge of the value of any 
problem pertaining to the building trades is deserving 
of considerable respect. It is this knowledge, along 
with some knowledge of cause and effect, and my simple 
and unvarnished methods of placing building matters 
before the American workmen, that have made my 
books so popular, and lured the working public into pur- 
chasing, at this writing, nearly two millions of them. 
And I have reason to hope that this volume will, like 
all my pre\dous ones, meet with a reasonable amount 
of appreciation from those who work, or guide the work 
of others, in cements, plasters, concretes and stuccos. 

Fred T. Hodgson. 



PARTI 

CONCRETES, CEMENTS, PLASTERS AND STUC. 

COS— THEIR USES AND METHODS 

OF WORKING SAME. 

INTRODUCTORY 

This book, or rather compilation, is largely made up 
of the very best material available on the subjects it 
proposes to discuss. All the latest improvements and 
methods in the mixing, proportioning and application 
of plaster, mortar, stucco and cement will be described 
and laid before the reader in as simple and plain a man- 
ner as possible. 

The art of using mortars in some shape or other, is 
as old as civilization, as we find evidences of its use in 
ruins that date long before historical times, not only 
in the older countries of Asia and Europe, but also in 
the ruins of Mexico, Central America and Peru; and 
the workmen who did their part, or most of this work, 
were evidently experts at the trade, for some of the 
remains of their work which have come down to us 
certainly show that the work was done by men who 
not only had a knowledge of their trade, but that they 
also possessed a fair knowledge of the peculiar qualities 
of the materials they used. ''Plastering," says Miller 
in his great work on Mortars, ''is one of the earliest 
instances of man's power of inductive reasoning, for 
when men built they plastered: at first, like the birds 
and the beavers, with mud; but they soon found out a 
more lasting and more comfortable method, and the 

7 



8 CEMENTS AND CONCRETES 

earliest efforts of civilization were directed to plaster- 
ing. The inquiry into it takes ns back to the dawn of 
social life until its origin becomes mythic and prehis- 
toric. In that dim, obscure period we cannot pene- 
trate far enough to see clearly, but the most distant 
glimpses we can obtain into it show us that man had 
very early attained almost to perfection in compound- 
ing material for plastering. In factj so far as we yet 
know, some of the earliest plastering which has re- 
mained to us excels, in its scientific composition, that 
which we use at the present day, telling of ages of ex- 
perimental attempts. The pyramids of Egypt contain 
plaster work executed at least four thousand years ago 
(some antiquaries, indeed, say a much longer period), 
and this, where wilful violence has not disturbed it, 
still exists in perfection, outvying in durability the 
very rock it covers, where this is not protected by its 
shield of plaster. Dr. Flinders Petrie, in his 'Pyra- 
mids and Temples of Gizeh, ' shows us how service- 
able and intellio'ent a co-operator with the painter, the 
sculptor, and the architect, was the plasterer of those 
early days, and that to his care and skill we owe almost 
all we know of the history of these distant times and 
their art. Indeed the plasterer's very tools do yet re- 
main to us, showing that the technical processes then 
were the same we now use, for there are in Dr. Petrie 's 
eoHecticn hand floats which in design, shape and pur- 
pose are precisely those which we use today. Even our 
newest invention of canvas plaster was well known 
then, and by it were made the masks which yet pre- 
serve on the mummy cases the lineaments of their occu- 
pants. " 

The plaster used by the Egyptians for their finest 
work was derived from burnt gypsum, and was there- 



INTRODUCTORY 9 

fore exactly the same as our "plaster of paris." Its 
base was of lime stucco, which, when used on partitions, 
was laid in reeds, laced together with cords, for lath- 
ing, and Mr. Miller, who has examined a fragment in 
Dr. Petrie's collection, finds it practically "three coat 
work," about % of an inch thick, haired and finished 
just as we do now. 

Plaster moulds and cast slabs exist, but there does not 
appear any evidence of piece moulding, nor does any 
evidence of the use of modelled work in plaster exist. 
That some process of indurating plaster was thus early 
known is evidenced by the plaster pavement at Tel-el 
Amarna, which is elaborately painted. The floor of 
this work is laid on brick; the first coat is of rough 
lime stucco about 1 inch thick, and the finishing coat 
of well-haired plaster about % inch thick, very smooth 
and fine, and showing evidence of trowelling, the set- 
ting out lines for the painting being formed by a struck 
cord before the surface was set, and the painting done 
on fresco. It is about 60 by 20, and formed the floor 
of the principal room of the harem of King Amenhotop 
IV., about fourteen hundred years before Christ, that 
is, between three thousand and four thour.and years 
ago. Long before this, plastering of fine quality 
existed in Egypt, and so long as its civilization con- 
tinued it aided the comfort of the dwellings of its 
people and the beauty of its temples. 

Nor was it merely for its beauty and comfort that 
plaster work was used. Even then its sanitary value 
was recognized, and the directions given in Leviticus 
xiv, 42-48, which was probably written about one hun- 
dred years before this date, show that the knowledge 
of its antiseptic qualities was widely spread, and the 
practice of it regarded as religious duty. 



10 CEMENTS AND CONCRETES 

Unfortunately there is no direct evidence that the 
adjacent Assyrian powers of Nineveh and Babylon used 
plaster work. Possibly the fine clay brought down by the 
rivers of the Euphrates and the Tigris sufficed for all 
their purposes. Their records are in it : their illustra- 
tions on the sculptured walls of their palaces are in 
stone, their painting is glazed on their bricks, and for 
them there seems to have been but little need for plas- 
ter work, nor do we find until the rise of Grecian art 
anything relating to our subject. 

Very early in Greek architecture we find the use of 
plaster, and in this case a true lime stucco of most ex- 
quisite composition, thin, fine and white. Some has 
been found at Mycenae, a city of Homeric date. We 
know that it existed in perfection in Greece about five 
hundred years before the Christian era. With this the 
temples were covered externally, and internally where 
they were not built of marble, and in some cases where 
they were. This fine stucco was often used as a ground 
on which to paint their decorative ornament, but not 
infrequently left quite plain in its larger masses, and 
some of it remains in very fair preservation even to 
this day. The Temple of Apollo at Bassae, built of 
yellow sandstone about 470 B. C, has on its columns 
the remains of a fine white stucco. 

Pavements of thick, hard plaster, stained, of various 
colors, were common in the Greek temples. One of 
these, that of the Temple of Jupiter Panhellenius at 
^gina, built about 570 B. C, is described by Cockerell 
as existing in the early part of the century, in good 
condition, though the temple itself was destroyed ; and 
I have seen at Agrigentum plaster exisjing in perfect 
state, though scarcely thicker than an egg-shell, on the 
sheltered parts of a temple built at least three hundred 



INTRODUCTORY H 

/ears before our era, whilst the unprotected stone was 
weather worn and decayed. 

What care the ancient Greeks bestowed on their 
stucco may be inferred from Pliny's statement that in 
the temple at Elis about 450 B. C, Panaenus, the 
nephew of Phidias, used for the groundwork of his 
picture ''stucco mixed with milk and saffron, and pol- 
ished with spittle rubbed on by the ball of the thumb, 
and," says he^ *'it still retains the odor of saffron." 
Lysippus, the first of the Greek ''realists" in sculpture, 
was the first we hear of who took casts of the faces of 
living sitters about 300 B. C, so the art of plaster cast- 
ing must have advanced a good deal by that time, as he 
made presents of copies to his friends. Afterwards we 
read of many sculptors who sent smaller plaster models 
of their works to friends. These were, however, prob- 
ably carved in the plaster rather than cast. 

Whether the Greeks used stucco for modelling is a 
somewhat doubtful point amongst antiquarians. From 
certain passages in classic writers I am induced to think 
they did. Pausanius, who describes the temple at Stym- 
phalus, an almost deserted and ruined city when he 
visited it about 130 A. D., describes the ceiling of the 
Temple of the Stymphalides, built about 400 B. C, as 
being "either of stucco or carved wood," he could not 
decide which, but his very doubt would imply that 
stucco or wood were equally common. Now, this ceil- 
ing was ornamented with panels and figures of the 
harpies — omens of evil, half woman and half bird, with 
outspread wings. He also mentions a statue of Bac- 
chus in "colored stucco." Of course these are not defi- 
nite proofs of early Greek stucco modelling, but as the 
city of Stymphalus had decayed and become depopu- 
lated before 200 B. C, there is certainly presumptive 



12 CEMENTS AND CONCRETES 

evidence of the ancient practice of the art. Again, fig- 
ures of unburnt earth are mentioned in contradistinc- 
tion to those of terra cotta, and sundry other allusions 
to plastic work occur, which lead me to the opinion that 
quite early in Greek art this mode of using plaster be- 
gan. At any rate, we know that it was early introduced 
into Grecia Magna — the earliest Southern Italian col- 
ony of the Greeks; and as colonists invariably preserve 
the customs and traditions of their fatherland even long 
after they have fallen into disuse in their native home, 
we can have no reasonable doubt but this art was im- 
ported rather than invented by them. Thence it spread 
to the Etruscans of Middle Italy, a cognate people to 
the Southern Greeks, by whom both plain and modelled 
stucco was largely used. The Etruscans, as we have 
seen, were more closely allied to the Greek than the 
Latin race, but in the course of time these two races 
amalgamated, the former bringing skill in handicraft, 
the latter lust of power, and patriotic love of country 
and of glory, whilst the Grecian element, which blended 
harmoniously with the first of these, added a love of art. 

This union, however, took long to ripen to artistic 
fruitfulness. The practical Etruscan element firstly 
constructed the roads and the sewers, and gave health to 
Rome. The Latins added to their territory until it em- 
braced half of Europe, giving wealth to Rome, and not 
till the luxury and comfort thus created did the artis- 
tic element of the Greek come in, giving beauty to 
Rome, and the day of decorative plaster work ap- 
proached its noontide glory, making Rome the attrac- 
tion of the world. The absorbance of Greece as a 
Roman province took place B. C. 145, and the loot of 
it began, giving an enormous impetus to Roman art. 
Thousands of statues were brought to Rome, and to 



INTRODUCTORY 13 

be deemed a connoisseur in things artistic or a patron 
of the arts became the fashionable ambition. But it 
was not until the century just preceding the Christian 
era that it became especially noteworthy. Of course 
there is hardly anything left to us of the very early 
plaster work of Rome. The constant search for some 
new thing was inimical to the old. Old structures were 
pulled down to make way for new, which in their turn 
gave way to newer, and until the age of Augustus we 
have but little of the early work left. Strabo, who 
visited Rome about this time, complains of the destruc- 
tion caused by the numerous fires, and continued pull- 
ing down of houses rendered necessary, for even pull- 
ing down and rebuilding in order to gratify the taste 
is but voluntary ruin; and Augustus, who boasted that 
''he found Rome of brick and left it of marble," in 
replacing the brick with marble destroyed the plaster 
work. How that plaster work was wrought we shall 
learn more from Vitruvius, who wrote his book on archi- 
tecture about 16 B. C, and dedicated it to the emperor, 
''in order to explain the rules and limits of art as a 
standard by which to test the merits of the buildings 
he had erected or might erect." 

Now, Vitruvius was a man who had travelled and 
seen much. He was with Julius Caesar as a military 
engineer in his African campaign in 46 B. C, or ten 
years after Caesar's invasion of Britain. Afterwards 
he became a designer of military engines, what we 
should call head of the Ordnance Department, and also 
a civil engineer, persuading himSelf that he had a 
pretty taste in architecture, just as though he were an 
R. E. of today. Thus he had a practical and also an 
artistic training, and here is what he says on matters 
connected with plaster work in Book VII, Chapter 11. 



14 CEAIEXTS AXD CONCRETES 

On tempering lime for stucco : "' " Tliis requires tliat the 
lime should be of the best qnality, and tempered a long 
time before it is tv anted for use : so that if any of it be 
not burnt enough, the length of time employed in slak- 
ing it mav brins the whole mass to the same consist- 
ency. " He then advises it to be chopped with iron 
hatchets, adding that "if the iron exhibits a glutinous 
substance adhering to it. it indicates the richness of the 
lime, and the thorough slaking of it." For cradling 
out. and for ceiling joists, he recommends "the wood 
to be of cypress, olive, heart of oak. box and juniper," as 
neither is liable to "rot or shrink."' For lathing he speci- 
fies ' ■ Greek reeds bruised and tied with cords made from 
Spanish broom." or if these are not procurable "marsh 
reeds tied with ccrds. " On these a coat of lime and 
sand is laid, and an additional coat of sand is laid on 
to it. As it sets it is then polished with chalk or marble. 
This for ceilings. For plaster on Avail he says: "The 
first coat on the walls is to be laid on as roushlv as 
possible, and while drying, the sand and coat spread 
thereon. When this work has dried, a second and a 
third coat is laid on. The sounder the sand and coat is, 
the more durable the work will be. The coat of marble 
dust then follows, and this is to be so prepared that 
when used it does not stick to the trowel. TVhilst the 
stucco is dr^ung, another thin coat is to be laid on : this 
is to be well worked and rubbed, then still another, 
finer than the last. Thus with three coats and the 
same number of marble dust coats the walls will be 
solid, and not liable to crack. The wall that is well 
covered with plaster and stucco, when well polished, 
not only shines, but reflects to the spectators the images 
falling on it. The plasterers of the Greeks not only 
make their stucco work hard bv adhering to these direc- 



INTRODUCTORY 15 

tions, but when the plaster is mixed, cause it to be beat- 
en with wooden staves by a great number of men, and 
use it after this preparation. Hence some persons cut- 
ting slabs of plaster from ancient walls use them for 
tables and mirrors." (Chapter III.) 

You will see by these remarks the great care taken 
through every process, and how guarded the watchful- 
ness over the selection of materials, and you will also 
note the retrospectiveness of Vitruvius' observation, 
how he felt that the work done before the frantic haste 
of his own time was the better: very much as we find 
now. Time is an ingredient in all good work, and its 
substitute difficult to find.* 

There are other "tips" contained in this work which 
are worth extraction, as, for instance, his instructions 
as how to plaster damp walls. In such case he prima- 
rily suggests a cavity wall, with ventilation to insure 
a thorough draught, and then. plastering it with "pot- 
sherd mortar," or carefully covering the rough plaster 
with pitch, which is then to be "lime whited over," to 
insure "the second coat of pounded potsherds adhering 
to it," when it may be finished as already described. 
Further, he refers to modelled plaster work which, he 
says, "ought to be used with a regard to propriety," 
and gives certain hints for its appropriate use. Speak- 
ing of pavements "used in the Grecian winter rooms, 
which are not only economical but useful," he advises 
"the earth to be excavated about two feet, and a foun- 
dation of potsherd well rammed in," and then a "com- 
position of pounded coal lime, sand and ashes is mixed 
up and spread thereover, half foot in thickness, per- 
fectly smooth and level. The surface then being rubbed 
with stone, it has the appearance of a black surface," 
"and the people, though barefoot, do not suffer from 



16 ceinIents and concretes 

cold on this sort of pavement." Now all this bespeaks 
not only theoretical knowledge, but practical observa- 
tion and experience, and was written nearly two thou- 
sand years ago, from which you can surmise how far 
advanced practical plastering had then become. This 
written evidence is almost all we have of the work of 
Vitruvius' own time, for even of the time of Augustus 
hardlv anvthing remains to us, as the great fire of 
Nero utterly destroyed the greater part of the city in 
the year A. D. 64:, and almost the only authenticated 
piece of plaster work done before or during his reign 
is the Tabula Iliaca, a bas-relief of the Siege of Troy, 
still preserved in the Capitol Museum at Rome. That 
this was modelled by Greek artists is proved by the fact 
that its inscriptions are all in the Greek language, and 
by some it is considered to be of very much greater an- 
tiquity. So much for the ancient history of the art 
of plastering, and I trust I will be pardoned if I con- 
tinue this sketch, bringing it down to a more recent 
period and show in what high respect the plasterers ' art 
was held in the Sixteenth Century, and later. Quoting 
from an old work, giving an account of the institution 
of ^ ' The Worshipful Company of Plaisterers, ' ' and mak- 
ing use of the quaint language then in use we are told 
that: "The Plaisterers' Company, which ranks as 
forty-sixth among the eighty-nine companies, was in- 
corporated by King Henry YII., on March 10, 1501, to 
search, and try, and make, and exercise due search as 
well in, upon, and of all manner of stuff touching and 
concerning the Art and Mystery of Pargettors, com- 
monly called Plaisterers, and upon all work and work- 
men in the said art or mystery, so that the said work 
miglit be just, true, and lawful, without any deceit or 
fraud whatsoever against the City of London or suburbs 



INTRODUCTORY 



17 



thereof. The Charter gave power to establish the Com- 
pany as the Guild or Fraternity in honour of the 
Blessed Virgin Mary, of men of the Mystery or Art of 
Pargettors in the City of London, commonly called 
Plaisterers, to be increased and augmented when neces- 
sary, and to be governed by a Master and two "War- 
dens, to be elected annually. The Master and Wardens 
and brotherhood were to be a body corporate, with per- 
petual succession and a common seal, and they were 
empowered to purchase and enjoy in fee and perpet- 
uity lands and other possessions in the City, suburbs 
and elsewhere. And the charter empowered the said 
Master and Wardens to sue and be sued as "The Mas- 
ter and Wardens of the Guild or Fraternity of the 
Blessed Mary of Pargettors, commonly called Plaister- 
ers, London. 



? ? 




THE OLD COAT OP AEMS, 



The Company under the powers to make examina- 
tions, appears to have inflicted fines on offending par- 
ties for using bad materials, and for bad vvorkmanship. 
Search days appear to have been annually appointed 
up to 1832, but not since, and the Company has not 
exercised any control over Plaisterers' work for many 
years. 



18 



CEMENTS AND CONCRETES 



Another charter was granted by Queen Elizabeth in 
1559, but it has been lost, and there is no record of 
the contents. The Queen granted a new charter in 
1597, which confirmed the privileges of the Company, 
and extended the authority of the Master and Wardens 
to and over all persons exercising the art of plaisterers, 
as well English as aliens and denizens inhabiting and 
exercising the said art within the City and suburbs and 
liberties, or within two miles of the City. 




TH2 PEBSBNT COAT OP ABUS, 



Charles II., by a charter dated June 19, 1679, con- 
firmed the privileges granted by the previous charters. 
Having in view the rebuilding of the City, he forbade 
any person to carry on simultaneously the trades of 
a mason, bricklayer or plaisterer, or to exercise or carry 
on the art of a plaisterer without having been appren- 
ticed seven years to the mystery. The jurisdiction of 
the Company was extended to three miles' distance 
from the City. 

There were two orders made by the Court of Alder- 
men (exemplified under the mayoralty se£il, April 1) 



INTRODUCTORY . 



19 



1585) for settling matters in dispute between the tilers 
and bricklayers and the plaisterers as to interfering in 
each other's trades. The observance of these orders 
was enforced by an order of the Privy Council dated 
June 1, 1613, and a general writ or precept issue to the 
same effect on August 13, 1613. 




Indian Centre-Piece. 



There was also an order of the Court of Aldermen 
(29 Elizabeth, February 14, 1586-7) relating to the 
number of apprentices to be kept by members. 

An act of Common Council was passed, under date 
of 18 James I., October 5, 1620. 

An act of Common Council (6 William and Mary, 
October 19, 1694) was also passed to compel all persons 
using the trade of plaisterer in the City of London or 



20 CEMENTS AND CONCRETES 

the liberties thereof, to become free of the Company 
under penalty to be recovered as therein mentioned. In 
the East the Art of ornamental plastering was weli 
known and almost universally practiced before Mahom- 
et established a new order of things, and the enriched 
plaster work of India, Persia and other Eastern Em- 
pires are evidences of the high character of the work- 
manship of the Oriental workers in plaster. . The 
Arabian and Moor brought back the Art of the Western 
World in the early part of the thirteenth century, 
and it is to them we owe the splendid plaster work of 
the Alhambra and other work still in existence in Spain. 
In the Mosque at Medina, built in 622, are still to be 
seen some fine specimens of old plaster Avork that was 
wrought on the building at the time of its completion. 
The Mosque of Ibu-tubun, Cairo, Egypt, which was fin- 
ished in A. D. 878, abounds T^dth beautiful plaster work. 
It contains a number of arches and arcades, the capi- 
tals of which, like the rest of the building, are enriched 
with plaster buds and flowers made in elaborate de- 
signs. Even in Damascus, thai old and far-off City 
indulged in ornamental plaster-work when the people 
of Western Europe were cutting one another's throats 
for political ascendency. We illustrate a few examples 
of old work taken from existing specimens. These will 
to some extent, give an idea of what the old plasterers 
could do. See illustrations attached. 

During the middle ages in Europe plastering and 
stucco existed only as a craft, and its highest function 
was to prepare a surface to be painted on. Sometimes 
it was used as an external protection from the weather 
but rarely was it employed for direct ornament. Some- 
times small ornaments were carved in plaster of Paris, 
but it played no important part in decorative Art, 



INTRODUCTORY 



21 



excepting perhaps, as gesso, though this belonged rather 
to the painter than the plasterer. Nor was it until the 
commencement of the Renaissance in Italy that it 
showed any symptoms of revival. 




■Arabesque krom the Great Mosque, Damascus. 



"With the commencement of the fifteenth century old 
learning and old arts began to be studied, the discovery 
of the art of printing and the consequent multiplication 
of the copies of the lore heretofore looked up in old 
manuscripts gave invention and progress new life, 



22 



CEMENTS AND CONCRETES 



Tvhich has lasted until the present day. Italy has al- 
ways been the nursing mother of plasterers, and in Mr. 
G T. Robinson's "Glimpse of the History of the Art 
and Craft/' he has shov/n something of her great and 
glorious past, and how she sent her sons over almost 
all Europe to raise the art and status of this craft. 




Persian Centre- Piece. 



Even during the depressing times of her history she 
religiously preserved its ancient traditions and pro- 
cesses, and in almost all her towns there was some one 
or two plasterers to whom was confided the restoration, 
the repair and the conservation of its frescoes or its 
stuccos. The art dwindled, but it survived. So late 
as 1851 an English architect, when sketching in the 



INTRODUCTORY 23 

Campo Santo at Pisa, found a plasterer busy in lov- 
ingly repairing portions of its old plaster work, which 
time and neglect had treated badly, and to wh6m he 
applied himself to learn the nature of the lime he used. 
So soft and free from caustic qualities was it that the 
painter could work on it in true fresco painting a few 
days or hours after it was repaired, and the modeller 
used it like clay. But until the very day the architect 
was leaving no definite information could he extract. 
At last, at a farewell dinner, when a bottle of wine 
had softened the way to the old man's heart, the plas- 
terer exclaimed, "And now, signor, I will show you 
my secret!" And immediately rising from the table, 
the two went off into the back streets of the town, when, 
taking a key from his pocket, the old man unlocked a 
door, and the two descended into a large vaulted base- 
ment, the remnant of an old palace. There amongst 
the planks and barrows, the architect dimly saw a row 
of large vats or barrels. Going to one of them, the old 
man tapped it with his key; it gave a hollow sound 
until the key nearly reached the bottom. "There, sig- 
nor! there is my grandfather! he is nearly done for." 
Proceeding to the next, he repeated the action, saying: 
' ' There, signor ! there is my father ! there is half of him 
left. ' ' The next barrel was nearly full. ' ' That 's me ! 
exclaimed he; and at the last barrel he chuckled at 
finding it more than half full: "That's for the little 
ones, signor!" Astonished at this barely understood 
explanation, the architect learned that it was the cus- 
tom of the old plasterers, whose trade descended from 
father to son for many successive generations, to care- 
fully preserve any fine white lime produced by burning 
fragments of pure statuary, and to each fill a barrel for 
his successors. This they turned over from time to 



24 



CEMENTS AND CONCRETES 



time, and let it ain — slake in the moist air of the vault, 
and so provide pure old lime for the future by which 
to preserve and repair the old works they venerated. 
After-inquiries showed that this was a common prac- 




PoRTioN OF A Ceiling from Teheran, Persia. 



tice in many an old town, and thus the value of old 
air-slaked lime, such as had been written about eighteen 
hundred years before, Avas preserved as a secret of the 
trade in Italy, whilst the rest of Europe was advocating 



INTRODUCTORY 



25 



the exclusive use of newly burnt and hot slaked lime. 
"Was there in the early part, indeed even in the middle 




DiAPFKEn Piaster PANEiiiNr. is riiE AihamuijX, Smin, Thikifenth Cesturv. 



of the present century, any plaster image seller who was 
not an Italian? Indeed, at this present time, almost 



26 



CEMENTS AND CONCRETES 



all the ' ' f ormatore " or piece moulders for the majority 
of the sculptors of Europe are of Italian nationality or 
descent, and chiefly by these has the national craft been 
maintained. 

When after the long European wars of the eighteenth 
and the commencement of the nineteenth century Italy 
had rest and power to ''make itself" (faro de se), the 
first revival of its industry was felt by her plasterers, 
and as there was then, as now^ more workmen than 




w^^stmwmm^^^MWfm. 




work, they emigrated to the neighboring countries; and 
the major part of the plasterers along the Revieda, in 
the southern provinces of Germany and Austria, are 
Italians who go off with and return with the swallows, 
to earn that wage the poverty of their own country 
cannot afford them. With this brief historical sum. 
mary I conclude the Introductory notice, and will now 
pass on to the more practical domain of the Plasterers* 
Art. 



MATERIALS. 

IJMES, CEMENTS, MORTARS, SAND, PLASTERS AND LATHS. 

LIMES. 

The Lime Principally Used for internal plastering 
is that calcined from carbonate of lime, in which the 
impurities do not exceed 6 per cent., and is known as 
fat lime, pure lime or rich lime. It is unfit for any 
purpose where strength is required, or in situations 
where it is exposed to the weather, as it has no setting 
power, and is easily dissolved by wet. 

Hydraulic Limes are those which, in order to set, do 
not require any outside influences, their own chemical 
composition of lime and silica, when burnt, being suf- 
ficient for the purpose. The name is given for their 
capability of setting and hardening under water. Hy- 
draulic limes are obtained mostly from the lias. 

Good Hydraulic Limes are obtained from many 
places in the United States and Canada, the best 
known is *'The Rosendale Hydraulic Cement." 

Artificial Hydraulic Limes may be made by mixing 
a sufficient quantity of clay with pure lime to obtain 
a composition like that of a good natural hydraulic 
limestone. The lime^ if soft, may be mixed with the 
clay and burnt raw, or, as is more usual, may be burnt, 
slaked, ground, and then mixed with the clay and re- 
burnt. 

The Purer the Lime the quicker will it slake. Great 
care should be taken that the lime is properly burnt 
or otherwise it will not slake properly, and will prob- 
ably **blow" in the work. 

27 



28 CEMENTS AND CONCRETES 

The Perfect Slaking of the burnt lime before being 
'ised is very important, as it will slake eventually, and 
cause blisters in the work. In order to effect thorough 
slaking, the lime should be ''run" as soon as the build- 
ing is commenced. It should not be used unless it has 
been slaked at least three weeks. 

A Bushel of Lime requires in slaking about a gallon 
and a half of water. 

Lime ivhicJi Slakes Quickly and with great heat is 
generally considered to be the best for plasterers' work. 

When Lime '^ Falls'' in dry weather without any 
sufficient apparent moisture, it is considered to foretell 
rain. 

The Lime Should Be Bun in couch on the site, where 
it can be seen by the architect. Care should be taken 
that as much lime is run as is required for the whole 
of the building. 

The Plasterer, partly, perhaps, to avoid the money 
outlaj^, and partly to avoid the necessity of having to 
cart awav anv lime, has a tendencv to run an insuf- 
ficient quantity of lime. The result of this is that he, 
commencing at the top, the usually less important part 
of the building, has used up his lime by the time he 
has reached the principal rooms on the ground floor, 
and has to have recourse to possibly insufficiently sea- 
soned lime, with an unfortunate effect on the work, as 
stated above. 

SAND. 

The Functions of Sand as used in plaster are (1) the 
production of regular shrinkage and the prevention of 
excessive shrinkage, otherwise cracking is the result; 
C2) to form channels for the crystallization. 



MATERIALS 29 

Sand should be clean, sharp, and hard. The size of 
the grains does not influence the strength of the mortar, 
but, of course, the finer the plaster is required to be 
the finer must the sand be. Fine sand is best for hy- 
draulic lime and coarse for fat limes, coarse stuff and 
Portland cement for floating. Uniformity of size is 
not desirable. 

The Proportion of Sand to Lime will vary consider- 
ably, according to circumstances, and is difficult to de- 
termine. One part of lime to two parts of sand is a 
usual mixture. 

Sand is Cheaper than Lime, and it must be remem- 
bered that this is an inducement to use too large a pro- 
portion of sand in order to cheapen the plaster. 

Sand is Obtained from rivers, pits, or the sea. Sea 
sand, or that from tidal rivers, should be avoided, as 
the salt never dries, and will come out on the surface 
sooner or later, discoloring the wall papers, paint, etc., 
and keeping the walls damp. 

» River Sand is often used, but it is not to be recom- 
mended, because the sharpness of the grains is worn 
off by the action of the running water. It is easily 
obtained, however, and the light color of much river 
sand causes it to be used in internal work with the 
white cements. * 

Pit Sand is the best. It sometimes contains loam or 
clay, which should be carefully washed out. 

All Sand for High-Class Plastering is best washed. 

HAIR. 

Hair is used in plaster in order to bind it together. 

Good Hair should be long, curled, strong, and clean. 
Ox or cow hair is most generally used, and there are 
three qualities. 



30 CEMENTS AND CONCRETES 

It Should Be Well Separated before being mixed 
with tbe plaster, and care should be taken in the mix- 
ing that the hai2?s are not broken. 

CEMENTS. 

Portland Cement, with a large proportion of sand, 
as much as 90 per cent., is useful for internal work; 
it may be used as a backing for a thin floating of the 
white cements. 

The Heavier and Slower in Setting cements are gen- 
erally the stronger; but in such plasterer's work as 
rendering walls the quicker setting cements may be used 
without disadvantage. 

Roman Cement is a ''natural" cement. It is liable 
to effloresce on the surface, but is useful where quick 
setting with expansion is required, as in underpinning 
or repairs, without any great ultimate strength. 

Other ''Natural Cemejits" very similar to Roman 
are Medina, Rosendale, Windsor, etc., and are also use- 
ful where quick setting is required. 

The Use of the Natural Cements is much restricted 
at the present time. as compared with artificial cements, 
such as Portland. 

Parian Cement; is valuable for internal work, by rea- 
son of its hardness, nonporosity, and quick setting 
properties. It is hence useful in cases where the walls, 
mouldings, etc., have to stand rough usage. It is also 
washable. This cement will not admit of being re- 
worked. 

Keene's Cement is one of the most useful of the 
artificial cements. It is harder than the other kinds 
made from plaster of Paris, and is much used for pilas- 
ters, columns, etc.^ as it sets quickly and can be pol- 
ished, and takes paint excellently. 



MATERIALS 31 

3Iartin's Cement is much the same as Keene's, and 
used principally for dadoes, etc. In proportion to its 
bulk it covers a large proportion of surface. It can 
be painted, etc., as Keene's. 

Robinson's Cement has many advantages, among 
which are its fire-resisting qualities and suitability for 
use on concrete. It is also cheaper than other like 
cements. 

Adamant is another white cement, which is useful for 
work where hardness, facility of application, quick dry- 
ing, and a fine surface are required. 

The Above Cements have plaster of Paris (calcined 
gypsum) for their base, and are only adapted for in- 
ternal uses, to which they are eminently suited. They 
can all be brought to a good surface, and can be painted 
almost at once. 

Selenitic Cement is based on the property which sul- 
phate of lime as plaster of Paris, when added to lime 
possessing hydraulic properties, has of causing its more 
rapid setting. It also increases the proportion of sand 
which it will bear. It is useful in plastering as a back- 
ing for the white cements, such as Parian. 

PLASTER OF PARIS. 

Plaster of Paris is made by the gentle calcination of 
gj^psum, previously ground. It is known in the plas- 
tering trade as plaster. 

The Principal Use of Plaster of Paris is in mixing 
with ordinary putty in order to produce greater rapid- 
ity in setting, but the fast setting plasters of Paris are 
not, of course, the best for working with, nor do they 
become as hard as the slower setting. 

The Proportion of Plaster of Paris to ordinary lime 
putty varies greatly from about 1 in 4 to 1 in 20, de-^ 



32 CEMENTS AND CONCRETES 

pending on circumstances, such as the state of the 
weather, the speed with which the work has to be fin- 
ished, etc. It is also used largely for cast ornaments, 
in cornices, etc., and, by reason of its quick setting and 
expansion when setting, for stopping holes, etc. 

LATHS. 

Fine, Cedar and Metal are used for laths for mod- 
ern work; only the best quality should be used. 

OaU Laths and Cypress formerly used, are very liable 
to warp. 

The Defects to Be Avoided in Latlis are sap, knots, 
crookedness, and undue smoothness. The sap decays; 
the knots weaken the laths; the crookedness interferes 
with the even laying on of the stuff; and the undue 
smoothness does not give sufficient hold for the plaster 
on the lath. 

Riven Latlis, split from the log along its fibres, are 
stronger than sawn laths, as in the latter process the 
fibres of the wood are often cut through. 

Latlis May Be Obtained in Three Sizes, namely: 
''Single" (average 1-8 in. to 3-16 in. thick), "lath and 
half" (average ^ in. thick) and "double" (% in. to 
% in. thick). 

The Thicker Laths should be used in the ceilings, be- 
cause of the strain upon them, and the thinner in ver- 
tical partitions, etc., where there is but little strain. 
Where walls and partitions have to stand rough usage 
the thicker laths are necessary. 

Laths Are Usually Spaced with about % in. between 
them for key. 

A Bunch of Laths usually contains a hundred pieces, 
and such a bunch nailed, with butt joints, cover about 



MATERIALS 33 

4% yds, super., and requires about 500 nails if nailed 
to joists 1 ft. from center to center. 

The Lengths of Laths vary from 3 ft. to 4 ft., the 
latter the usual length. 

Laths Are Best Nailed so as to Break Joint entirely, 
as for various reasons there is a tendency to crack along 
the line of the joints if nailed with the butt ends in a 
row. This may be obviated by using 3 ft. and 4 ft. laths 
together. Ceilings are much stronger if so nailed. 
Laths, however, are usually nailed in bays, about 4 ft. 
or 5 ft. deep. 

Every Lath should be nailed at each end, and wher- 
ever it crosses a joist or stud. 

Lap Joints at the end of laths, which are often made 
in order to save nails, should not be allowed as this 
leaves only % in. for the thickness of plaster. Butt 
joints should always be made. 

Joists, etc., which are thicker than 2 in. should have 
small fillets nailed on their under side or be counter- 
lathed, so that the timber surface of attachment be re- 
duced to a minimum and the key be not interfered with. 

Walls which are liable to damp are sometimes bat- 
tened or strapped. 

Metal Lathing is now extensively used for its fire- 
proof qualities and freedom from rot or harboring of 
vermin. 

Lathing Nails are usually of iron — galvanized, cut, 
wire, or cast; where oak laths are used, the nails 
should be galvanized or wrought. Galvanized nails 
should also be used with white cement work. Zinc 
nails, which are expensive, are used in very good work, 
because of the possibility of the discoloration of the 
plaster by the rusting of iron nails. 



34 CEMENTS AND CONCRETES 

Tlie Length of Lathing nails depends on the thick- 
ness of the laths, % i^- ^ong nails being used for shin- 
gle laths, 1 in. nails for lath and half ^aths, and 1^4 i^- 
nails for donble laths. 

MEMORANDA. 

One Yard Rendering requires 1-3 cu. ft. lime, 14 cu. 
ft. sand. 2^2 oz. hair, and 1% gal. water. One yard 
render and set reqnires % en. ft. lime, i/o en. ft. sand, 
3 oz. hair, and 2 gal. water. 

One yard render, 2 coats and set, requires 3-5 cu. ft. 
lime, 2-3 cu. ft. sand, 3 oz. hair, and 2^^ gal. water. 

One yard render and float requires % cu. ft. lime, 
% cu. ft. sand, 2X^ oz. hair, and 2% gal. water. 

One yard render, float and set, reciuires 3-5 cu. ft. 
lime, % ft. sand, 3i^ oz. hair, and 2% gal. water. 

Two bushels of gray lime, or 3 of blue lias lime, or 
3 of Roman cement, or 2 of Portland cement, or 14 lbs. 
plaster of Paris, ecjual one bag. 

1 lb. hair is allowed to 2 cu. ft. of coarse stuff for 
good work, and 3 cu. ft. for common work. 

100 yd. super, of lime whiting, if once done requires 
1% cu. ft. of lime; and if twice done, 2 cu. ft. of lime. 



WORKMANSHIP. 



EXTERNAL WORK. 



Portland Cement is unquestionably the best material 
for external plastering. For weather resisting proper- 
ties, strength, and capacity for moulding and painting, 
it is unequalled. 

The Cement for Rendering requires to be mixed with 
sand in the proportion of about 1 of cement to 4 of 
sand, but for projecting cornices, etc., the proportion 
of sand should be only about half this, as, of course, the 
addition of sand decreases the adhesive power of the 
cement. The fining coat is mixed in the proportions of 
about 2 to 1. 

• External Facades in Portland Cement are usually 
laid in two coats; the first coat, known as the rendering 
or floating coat, is worked to screeds, and is from % 
in. to % in. thick. This coat must be carefully cleared 
and well wetted for the second coat, which is known 
as the finishing or fining coat, which is about 3-16 in. 
thick, and is worked with a hand float. 

The Key for External Plastering on brick work may 
be obtained either by building the walls roughly with 
the mortar projecting or by raking the joints at least 
% in. Stone work should be hacked. 

The Surface Mnst Be Well Wetted, or the wall will 
absorb the water from the rendering coat. 

There is a Tendency to Mix Fat Lime with Portland 
cement in order to make it work more freely, but this 
should not be allowed. 

35 



36 CEMENTS AND CONCRETES 

Stucco is the term which is loosely applied to all 
kinds of external plastering, whether of lime or cement. 
An enormous amount of "stucco" was done at the end 
of the eighteenth century and the beginning of the 
nineteenth, but is now out of fashion, except for coun- 
try and suburban residences. The term is also applied 
to some forms of internal plastering. The principal 
varieties of stucco are common, rough, bastard, and 
trowelled, but cement has largely superseded them. 

Common Stucco_. was principally employed for ex- 
terior work, and was composed of 1 part hydraulic lime 
and 3 parts sand. The surface of the wall should be 
rough and wet as for Portland cement rendering. 

Bough Stucco was used on a floated ground in po- 
sitions where it was desired to imitate stone. It was 
worked with a hand float covered with a material such 
as rough cloth, in order to raise the sand and produce 
a stone-like appearance. Cement is now used for the 
same purpose. 

Bastai^d Stucco and Trowelled Stucco were chieflv 
adapted for painted internal work, and each is laid on 
the second coat as a finish; the first and second coats 
being as for ordinary three-coat work. 

Troivelled Stucco consists of 1 part sand to 2 parts 
fine stuff. It is worked with the hand float till a very 
fine smooth surface is produced. 

Bastard Stucco contains a little hair and has not so 
much labor expended upon it. 

Sgraffito is the name given to ornament which is 
scratched on plaster work. Patterns may be obtained 
by laying differently colored coats (usually two or 
three) on ordinary roughened Portland cement ren- 
dering, and removing portions of each coat in the form 
of a pattern. 



WORKMANSHIP 37 

The Design for the Sgraffito is applied in a cartoon 
and pricked and pounced on the work in the usual way. 
If more colors are required than the coats provide, the 
background may be washed and a combination of 
sgraffito and fresco used. The cutting should be deep 
enough to give a sharp appearance, but not too deep 
tc hold dirt and wet. 

Rough Cast, also known as pebble dashing, is the 
coarsest kind of external plastering. It is very durable 
if properly mixed. Its use in this country dates back 
to very early times. The wall is first plastered, and 
gravel, shingle, or other materials such as spar, broken 
bricks and glass bottles, broken pottery, etc., are thrown 
or dashed at it while it is soft. If the gravel is mixed 
and laid with the plaster there is a tendency in laying 
for it to tear the plaster away from the wall, and as 
the gravel is covered with plaster its appearance is not 
so good. The lime for rough cast should be weather 
resisting, and is generally used hot. 

Depeter is a form of rough cast on which the gravel 
is pressed in by the hand. Ornamental patterns in 
color may be worked in it. Effective but simple deco- 
rations for external plaster may be made in various 
ways. Patterns, such as sunflowers, etc., may be in- 
cised in it, and a very effective decoration has been 
obtained by merely tapping the plaster with a scratch 
six or seven times alternately in a diaper pattern. In 
half-timber work the plaster is much more pleasing if 
carefully laid with a carelessly unlevel surface, and, of 
course, set back from the timber face about % in. 

INTERNAL WORK. 

Lime Plastering is compounded of lime, sand, hair, 
and water. The proportions of these materials vary 



38 CEMENTS AND CONCRETES 

according to their nature and the position of the pias- 
ter. For successful work good materials and skillful 
mixing are essential. It is applied in one, two, or three 
coats, and by the number of these the plaster is named. 

The Thinner the Coats of plaster are the better, as 
the plaster has a better chance of drying and harden- 
ing. 

One-Coat Work, necessarily the commonest and 
cheapest, is limited to very inferior buildings, such as 
outhouses and places where it will not be seen, as be- 
hind skirtings. One-coat work on laths is specified as 
'4ath and lay," or "lath and plaster," and on walk 
simply as ''render." 

Two-Coat Work is that usually em^ployed in inferior 
work, such as factories, warehouses, etc., but it is also 
used for the least important rooms in better class build- 
ings. Common setting for walls and ceilings is gener- 
ally used for this class of work. Two-coat work on 
laths is specified as "lath, lay, and set," or "lath, plas- 
ter, and set," and on walls as "render, and set." 

Three-Coat TTor/c is that used in all good buildings, 
and forms a most satisfactory wall finish, when well 
done. Three-coat work on laths is specified as "lath, 
lay, float, and set," or "lath, plaster, float, and set," 
and on walls as "render, float, and set." 

The Processes in Plastering ordinary three-coat work 
are as follows : 

For the First Coat a layer of well-haired coarse stuff 
known as pricking-up is laid to a thickness of about 
% in. This should be laid diagonally and with each 
trowelful overlapping. If on laths it should be soft 
enough to be well worked through them to form a key. 
The surface is then scratched with a lath to form a 
key for the r.^:-"- cr^r.'" Iv. '\L^'?z ab'^'^t 1 i:i. apart. It is 



WORKMANSHIP 39 

ready for the second coat when too hard to receive an 
impression from ordinary pressure. 

The Coarse Stuff used in the first coat is mortar com- 
posed of sand and lime, usually in the proportions of 2 
to 1, with plenty of hair, so that when a trowelful is 
taken up it holds well together and does not drop. 

The Second Coat known as floating, is next laid. 
Four processes are involved in laying the second coat, 
namely: Bunning the screeds, filling in the spaces, 
scouring and keying the surface. The scouring is done 
with a hand float, the surface being sprinkled by a 
brush during the process. The keying consists in lining 
the scoured surface with a broom or nail float to form 
an adhesive surface for the finishing coat. 

The Floating is of finer quality than the coarse stuff, 
it does not contain as much hair, and is used in a softer 
state. 

The Third Coat is the finishing coat, and is known 
as the setting coat. Great care must be taken in laying 
this coat in order to obtain uniformity of surface, color, 
smoothness, and hardness. The second coat should be 
uniformly keyed, clean and damp before the third is 
laid. The processes involved are laying, scouring, trow- 
elling, and brushing. 

Fine Stuff,- which should be used for the finishing 
coat if the walls are to be papered, consists of pure 
lime, slaked and then saturated till semi-fluid, and al- 
lowed to stand till the water has evaporated and it 
forms a paste. It may then be thoroughly mixed with 
fine sand in the proportion of 3 parts of sand to 1 part 
of fine stuff. 

Plasterers' Putty is much like fine stuff, but is care- 
fully sieved. 



40 CEMENTS AND CONCRETES 

Gauged Stuff is plasterers' putty and plaster of 
Paris in the proportion of three or four to one. If too 
much plaster is used it cracks in setting. It is largely 
used in cornices, and also where the second coat is not 
allowed time to dry, and the work has to be done in a 
Imrr}^ As it sets rapidly, it must be mixed in small 
quantities. 

The White Cements (such as Parian, etc.), of which 
plaster of Paris is the base^ are usually laid in two 
coats; the first, of cement and sand, is about % in. to 
% in. thick, and the second of the cement neat. 

Cracks in Plaster Work are caused, apart from the 
natural settlement of the building and the use of in- 
ferior materials and workmanship, by the too fast dry- 
ing of the work, the laying of the plaster on walls of 
too great suction, by laying one coat on another before 
the lower one has properly set, and by the use of too 
little sand. 

Joist Lines on Ceilings are very unsightly, and are 
caused by the filtration of dust through the intervening 
spaces. They may be prevented by using a good thick- 
ness of plaster, and working it well, that it may be hard 
and nonabsorbent and as the dust comes from the top 
and filters through, by protecting the upper side of the 
plaster. 

Pugging consists in laying a quantity of plaster be- 
tween the joists of a floor or between the studding of 
a partition for the purpose of preventing the passage 
of sounds or odors. In the first case, which is the more 
common, the plaster is laid on thin, rough boards fixed 
to battons on the sides of the joists; in the second case, 
which is called ' ' counterlathing " in some parts of the 
country, by plastering on laths nailed between the par- 
tition studs. 



WORKMANSHIP 41 

Pugging Should Not Be Used Too Wet. There are 
three objections to this — the first that it takes a very 
long and inconvenient time in drying; and secondly, 
that the water is liable to be absorbed by the wood, 
and to cause it to rot ; and thirdly, it is liable to crack 
in the drying. For this last reason it should always be 
laid in two coats. 

The Battons should all be nailed at an equal depth 
from the tops of the joists, and the plaster should be 
of an equal thickness throughout, which is obtained by 
drawing a trammel along the joists. 

Mineral Wool is far more sanitary than ordinary 
pugging, has considerable sound and fire resisting qual- 
ities, it does not absorb moisture and so rot the laths 
and timbers, is a preventive of vermin, and is light in 
weight. 

Lime Whiting or Whitewash which is lime dissolved 
in water, is a useful and sanitary covering for the 
walls of cellars and outhouses. 

If Lime-Whited Walls Have to Be Plastered, the wall 
should be first carefully picked, as if the lime is left on, 
the plaster is liable to scale. 

Fibrous Plaster is composed of plaster, canvas, wood, 
etc. It is light and dry and can be quickly fixed. 

Ornamental Plaster ceilings may be either modelled 
throughout in situ, or cast in pieces, or formed by work- 
ing the ornament on a previously formed flat ceiling. 
The first method is the more costly, but more feeling 
is thereby obtained. 



SPECIFICATION CLAUSES. 

MATERIALS. 

1. The sand for plastering is to be fresh-water river, 
or pit sand, and free from earthy, loamy, or saline 
material, to be well screened, and to be washed if re- 
quired. 

2. The laths to be straight-riven or saron pine of the 
strength known as lath and half, well nailed with lin. 
oxidized lath nails, properly spaced for key, and with 
butt-headed joints, double nailed, and breaking joint 
in 3 ft. widths. 

The lathing to be "Expanded metal," No. — gauge. 

3. The lime for coarse stuff to be approved well- 
burnt grey-stone lime, to be run at least one month 
before being required for use, to be kept clean, and 
well mixed as required with two parts sand and one 
part lime. 

4. The coarse stuff for ceilings, lath partitions, and 
elsewhere where directed to have 1 lb. of good, long 
curled cowhair, free from grease, leading, or other im- 
purities, well beaten in^ and incorporated with every 
3 cu. ft. of coarse stuff. 

5. Approved lime, free from lumps, flares, or core, 
is to be used for setting, putty, etc., and is to be run 
at least one month before being required for use. 

6. The Portland cement is to be of the best quality 
and description for plastering purposes, from an ap- 
proved manufacturer, and must on no account be used 
fresh, but be spread out to cool for at least . : . . weeks 
in a dry shed or room. 

42 



SPECIFICATION CLAUSES 43 

All suitable cement and all other materials required 
in plastering are to be of the best of their respective 
kinds and descriptions. 

7. Provide all plasterers' plant, necessary scaffold- 
ings, tools, moulds, running rules, straight edges, tem- 
plates, etc., of every kind and description necessary for 
the proper execution of the work. 



WORKMANSHIP. 

8. Lath, plaster, float, and set all wood joist ceil- 
ings, soffits, and stud partitions, and finish partitions to 
line in trowelled stucco. 

The concrete ceilings and soffits are to be well hacked^ 
for key and floated and set in gauged stuff, and the 
concrete partitions are to be floated and set. 

Do all dubbing out where required to concrete ceil- 
ings, soffits, and partitions in gauged stuff. 

The concrete soffits of strong rooms to be finished 
with one coat of putty gauged with plaster only. 

9. Cover all chases containing pipes, etc., with heavy 
wire lathing suitable for plastering on, securing the 
same in a thorough manner. The wire lathing to be 
wetted in lime water before being put on. 

10. Render, float, and set all walls where not other- 
wise described. The walls to to be finished in 

trowelled stucco. 

11. All cornices and moulded work throughout to 
be run clean and accurately to the sections given. 

All mitres and returns to be truly worked, and all 
enrichments and modelling to be to architect's ap- 
proval, and strictly in accordance with the models and 
instructions given. 

Run moulded plaster cornices girt to ... . rooms. 



44 CEMENTS AND CONCRETES 

with all mitres, returned, stopped, and mitred ends, 
etc., as required. 

The cornices to .... are to be run in fibrous plas- 
ter, fitted and fixed with proper oxidized nails, and 
made good to. 

12. All narrow reveals, splays, and returns to be 
finished in suitable cement on a Portland cement back- 
ing. 

Run strong cement angles and arrises on Portland 
cement backing to all projecting angles except the fol- 
lowing, which are to be moulded, viz. : 

Run rounded angles to of 3 in. girt in strong 

cement as before. 

Run avolo moulded angles 3 in. girt with 2 in. wings 
to .... opening, finished with moulded stops and short 
lengths of angle and arris to detail, all in best cement. 

All exposed surfaces of concrete lintels and girder 
casings are to be finished in white cement internally 
and Portland cement externally, kept flush with faces 
of brickwork; all with arrises and angles excepting 
those otherwise described. 

13. Run Portland cement flush skirting 9 in. high 
to basement, where plastered, with flush head to top and 
trowelled face. 

The skirting to , to be 12 in. high and 1 in. 

projection, sunk and twice moulded in white on Port- 
land cement backing. 

Float off the concrete floors of .... in Portland ce- 
ment to the required level to receive mosaic and the 
pavings. 

14. Run all necessary quirks, spla>s, arrises, etc., 
and make good to all mantelpieces; cut away for and 
make good after all other trades^ and cut out and make 



SPECIFICATION CLAUSES ^ 

good all cracks, blisters, and other defects, and leave 
plaster work perfect at completion. 

15. Ding walls where shown on plans with a coat of 
Portland cement 1 part, sand 2 parts, pea-grit 1 part, 
and ground chalk 1 part. Finish walls where shown 
with a rough coat of Portland cement 1 part and sand 
3 parts, and rough cast with fine pea-grit. 

16. Stop and twice lime white soffits and walls of . . 

17. Twice distemper white all ceilings, soffits, and 
cornices, and twice distemper to approved tints the 
walls of all rooms. 



PREPARATION OF BILL OF QUANTITIES. 

MATERIALS. 

Materials and Plant, etc. — 1 to 7. These items ap- 
pear in the heading under Specification clauses. 

WORKMANSHIP. 

Ceilmgs, Partitions, and Walls. — 8 and 10. These 
are all billed at per yd. super, including lathing where 
required, also hacking concrete and any dubbing in the 
latter, stating the thickness. Keep all plaster work 
less than 12 in. wide separate in "narrow widths." 

WirelatJiing. — 9. These being narrow, it is advisable 
to measure them at per ft. run, stating the width. 

Cornices. — 11. Cornices and mouldings under 12 in. 
girt are measured at per ft. run and those over this 
girt at per ft. super, number all mitres, stoppings, etc. ; 
those to the running items following same, and those 
to the superficial items averaged for girt. See whether 
bracketing is required; if so, take the girt required at 
per ft. super., numbering angle brackets to mitres and 
returned ends, and averaging the girt. 

Measure the walls and ceilings less by the height and 
projection of the cornice, and add to the girt of the 
cornice 2 in. (i. e., 1 in. for each edge) for the portion 
up to the ceiling and walls. 

Enrichments are measured at per ft. run, giving the 
girt and description, and including the modelling. If 

46 



BILL OF QUANTITIES 47 

of exceptional character, a provision for modelling is 
sometimes inserted. 

Angles. — 12. These appear in bill in feet run with 
the girt of moulding or bead (if any) and also the 
widths of returns. Number the stops, mitres, etc., al- 
lowing each to follow the item to which they apply. 

The finishings to concrete beams, lintels, etc., is kept 
separate as in "narrow widths to beams, etc.," and all 
arrises, etc., being measured at per ft. run. 

Skirtings or Dadoes. — 13. Describe skirtings or dadoes 
giving height and projection, and also finish at top, and 
measure at per ft. run, numbering all mitres, ends, etc. 
Include the dubbing with the item. The general wall 
plastering is deducted for these. 

Floating for mosaic and tile pavings appears in the 
bill in yard super. 

Quirks. — 14. Labor to splays, quirks, arrises, etc., 
are measured at per ft. run. 

The attendance on trades is frequently measured in 
detail, as ' ' making good around mantels "or gratings, 
etc. 

The cutting-out and making good appears at the end 
of the bill in the form here given. 

Rough Cast. — 15. As clauses 8 and 10. 

Lime Whiting and Distempering. — 16 and 17. These 
appear in the bill in yd. super. In the case of distem- 
pering, if the colors are in any way special mention 
this, and also if in dadoes and filling, taking the di- 
viding line in feet run. 

Distempering on cornices is usually measured in ft. 
super., stating the number of tints, and if lines picked 
out in ft. run ; as is also distempering on enrichments, 
taking the latter as "extra to," the distempering to 
cornices being measured over enrichments. 



48 CEMENTS AND CONCRETES 

LATHS GENER.VLLY. 

General opinion is undoubtedly in favor of split 
laths, and split laths are sometimes specified by archi- 
tects for ceilings and partitions. Sawn laths, unless 
cut from specially selected straight-grained stuff, would 
most assuredly have weak places from uneven grain, 
and in order to avoid this weakness the sawn laths 
would have to be made thicker than split laths, and 
only the best quality should be used. Oak laths, for- 
merly used, are very liable to warp. The defects that 
are to be avoided in laths are sap, knots, crookedness, 
and undue smoothness. The sap decays; the knots 
weaken the laths; the crookedness interferes with the 
even laying on of the stuff, and the undue smoothness 
does not give sufficient hold for the plaster on the lath. 
Riven laths, split from the log along its fibres, are 
stronger than sawn laths, as in the latter process the 
fibres of the wood are often cut through. Sawn laths 
are, however, cheaper than riven laths, and have super- 
seded them, which is not desirable in good work. Thick 
laths, because of the strain upon them, should be used 
in the ceilings, and the thinner laths should be used in 
vertical partitions, etc., where the strain is but small. 
Some walls and partitions have to stand rough usage; 
in such cases the thicker laths are necessary. Laths are 
usually spaced with about % in. between them for key. 
A bunch of laths usuallv contains 360 lin. ft. and such 
a bunch nailed with butt joints, covers about 4% super, 
yd., and requires about 400 nails if the laths are nailed 
to joists 16 in. from center to center. The length of 
laths varies from 3 ft. to 4 ft. Laths are best nailed so 
as to break joint entirely, because, for various reasons, 
there is a tendency to crack along the line of the joints 



BILL OF QUANTITIES 49 

if the laths are nailed with the butt ends in a row. This 
may be obviated by breaking joints; ceilings are much 
stronger if the laths are nailed in this way. Laths, 
however, are usually nailed in bays, about 4 ft. or 5 ft. 
deep. Every lath should be nailed at each end, and also 
at the place where the lath crosses a joist or stud. Lap 
joints at the end of laths, which are often made in or- 
der to save nails, should not be allowed, as this leaves 
only 14 ill- for the thickness of plaster. Butt joints 
should always be made. Joists, etc., that are thicker 
than two in., should have small fillets nailed to the un- 
der side, or be counter lathed, so that the timber surface 
of attachment may be reduced to a minimum and the 
key not interfered with. 

Lathing nails are usually of iron, and are galvanized, 
cut, wrought, or cast; where oak laths are used, the 
nails should be oxidized or wrought. Oxidized nails 
should also be used with white cement work. Zinc nails, 
which are expensive, are used in very good work, be- 
cause of the possibility of the discoloration of the plas- 
ter by the rusting of iron nails. The length of lathing 
nails depends on the thickness of the laths, % in. nails 
being used for single laths, and ly^ in. nails for double 
laths. 



TOOLS AXD APPLIANCES USED BY THE 

PLASTEKEE. . 

The illustrations shown at Figs. 1 and 2 show a num- 
ber of tools and appliances made use of by the plas- 
terer, and others — special — will be shoAvn further on. 
when it is necessari' to describe and illustrate some 
special process or method of working. The tools the 
plasterer requires are many and varied, and may be 
enumerated about as follows : Thev consist of moulds 
for running cornices, and center moulds, which may 
never be used only in the one piece of work, as the de- 
signs and stvles of cornices and centers are continuallv 
changing. As these tools do not cost much, however, 
the changes do not fall heavily on the workman : but it 
is as well, whenever it can be done, to charge each 
mould against its own particular job of work. A good 
spade and shovel will be absolutely necessary to the 
plasterer's outfit, and will be among the first tools he 
will require. These should be light and strong, and 
Avell handled, or helved : after using' thev should have 
all the lime and mortar cleaned off them, and should 
be placed away where they will not be exposed to the 
weather. 

The following list and descriptions of tools will give 
a new beginner an idea of the kind and character of 
tools he will be likely to require before he can success- 
fully carry on the plastering business. ]\Iost of these 
tools will be illustrated further on : 

The Hoes and Drags. — These are tools so well known 
that they require no description here. They are used 

50 



TOOLS AND APPLIANCES 



51 




52 CEMENTS AND CONCRETES 

chiefly for mixing hair in the mortar, and for loosening 
mortar when too ''stiff/' or when it has developed a 
tendency to "set." They are also used for preparing 
''putty" and fine "stuff." (See Fig. 2.) 

The Hawk, which is a square board about thirteen 
inches square, with a short handle on the under side. 
It is used for holding stuff while the operator is at 
work. It is generally made of pine or some other light 
Avood; it is made thin on the edges, being -beveled from 
the center on the under side to each of the four edges; 
the handle should be about six inches long, and one and 
a half inches in diameter. 

The Mortar-Board is a board similar to a table top, 
and is about forty inches square; it is made by joint- 
ing two or more boards together, which are secured by 
two battens, and screws or nails. It is used for holding 
the mortar delivered from the hod direct by the laborer. 

Trowels, which are of two kinds : the ordinary trowel, 
which is formed of light steel four inches wide and 
about twelve inches long; this is the laying and smooth- 
ing toolj and is the most important in a plasterer 's out- 
fit. The other is termed a gauging trowel, and is used 
for gauging fine stuff for courses, etc.; it varies in size 
from three to seven inches in length. 

Of Floats, which are used for floating, there are three 
kinds, viz. : the darby, which is not a proper float, is 
single or double, as may be required; the single being 
for one man to use, the double for two. The single one 
should be four feet five inches long, and about four 
inches wide, with a handle near one end, like a hawk 
handle, and a cleat near the other end running length- 
wise of the blade; the long darbys have a hawk handle 
on each end. The hard float, which is used in finishing, 
and the quick float, Avhich is us^d m floating angles. 



TOOLS AND APPLIANCES 



53 



H^nc^ f^oeyf 



H^n^k Aie3r(^/r7 7ro^&/. 





7ro/yS/s. 



(3^ur6/n^ Z^/^g/L 




A4ode///n§ looh 



NO. 2. 



54 CEMENTS AND CONCRETES 

The hard float is made of good pine, and has a semi- 
circular handle on the back; a strip of hard wood is 
sometimes dovetailed into the blade, and the handle is 
screwed fast to the strip pre^'ions to the latter being 
driven in the dovetail; this is a good way, as there are 
no nails then driven through the blade, which, by the 
rapid wearing of the latter, would soon project above 
the blade and scratch the plaster where it was intended 
to have it smooth. The quick float is seldom used in 
this country; it is shaped like the angle it is intended 
to work down, and is a trifle handier for this purpose 
than the ordinarv hard float. 

Moulds. — These are used for running stucco cornices, 
and are infinite in shape and variety. The reverse of 
the contour of the cornice is cut out of sheet copper or 
iron, and is firmly attached to a piece of wood which 
is also cut out the reverse shape of the intended mould- 
ing. Their uses will be explained under the head of 
Operations. Moulds or matrices for leaves, flowers, or 
other ornaments are made of plaster and glue, or bees- 
wax; these will be discussed hereafter. 

Center-Moulds are made on the same principle as the 
reverse moulds for linear cornices, with an arm at- 
tached which is perforated at different radii to suit the 
diameter of center-piece. Sometimes the moulds for 
cornicing are so formed, by placing the plates at an an- 
gle of forty-five degrees, that they will finish the cor- 
nice right into the angle and form the mitre : more fre- 
quently, however, the mitres are finished by hand. 

The Pointer is nearly the same shape as a bricklayer's 
trowel, but it is not so large, being only about four 
inches long. It is chiefly used for small jobbing, or 
mending broken or defective v\^ork. 



TOOLS AND APPLIANCES 55 

The Paddle is simply a piece of pine wood less than 
three inches wide and six long, by one thick ; it is made 
wedge shaped on one end, the other end being rounded 
off for a handle. Its use is to carry stuff into angles 
when finishing. 

Stopping and Picking-Out Tools, or, as they are fre- ^ 
quently called, Mitering Tools, are made of fine steel 
plate, seven or eight inches long, and of various widths 
and shapes. They are used for modeling, and for fin- 
ishing mitres and returns to cornices by hand where the 
moulds cannot work. 

Mitering-Bod. — This is a tool one foot or more long, 
and about one-eighth of an inch thick, and three inches 
wide^ the longest edge is sharp, and one end is bev- 
elled off to about thirty degrees. It is used for clean- 
ing out quirks in mouldings, angles, and cornices. 

The Operator also requires a good whitewashing 
brush with a short handle. The best should be ob- 
tained, as it will prove the cheapest in the end. 

A Scratcher is generally made of short pieces of pine 
two inches wide and one inch thick; three or four of 
them are nailed to two cleats, and are placed about an 
inch apart. The center slat should be about eighteen 
inches longer than the others, so as to form a handle.' 
See illustrations. The slats on the opposite end to the 
handle should be cut off square with one side and point- 
ed. Its use is to make grooves, or bond in what is called 
the scratch coat. When completed it has somewhat the 
appearance of a gridiron. 

Hod. — This is formed by two boards, eleven and 
twelve inches wide, respectively, and eighteen inches 
long, the wide board being nailed on the edge of the 
narrow^ one, making a right-angled trough; one end is 
closed, and the end piece is rounded over the top; the 



56 CEMENTS AND CONCRETES 

boards forming the sides are rounded at the opening. 
A handle about four feet long and two inches in diam- 
eter is then fastened about two inches forward of the 
middle nearer to the open end, and a piece of wood 
called a pad is fitted with a groove on the angle just 
back of the handle. The object of this block is to pre- 
vent the arris of the hod from chafing the shoulder of 
the laborer. Much controversy has taken place among 
workmen at various times regarding the exact size of 
hod, but this, I think, should be governed more by the 
strength of the person who has to use the particular 
hod than by any fixed rules. Hods for carrying mortar 
need not be so large as hods intended for carrying 
bricks. (See No. 2^ Fig. 1.) 

Sieve. — This is used for straining through putty for 
finishing; it requires to be very fine for the purpose. 
Sometimes a hair sieve is used, but they are not last- 
ing, and should never be used when a wire sieve is ob- 
tainable. Sometimes a hair sieve may prove convenient 
where dry plaster or cements have to be run through a 
sieve of some kind before it can be used; so, on the 
whole, the plasterer who desires a full and complete 
outfit, should provide himself with one good hair sieve, 
and at least two sieves of ^vire. (See Fig. 7, No. 1.) 

Sand Screens are usually twenty-one inches wide in- 
side by about six feet long. On small work they are 
stood up at an angle of forty-five or more degrees, and 
the sand is shovelled against them; in some large works 
the screen is suspended, and one man shovels in the 
sand and a second one swings or shakes the screen. 
These screens, to be lasting, should have their sides and 
ends made of sheet iron, and the bottom should be 
formed with parallel rods of small round iron having 
wires running across them at regular intervals. These 



TOOLS AND APPLIANCES 57 

cross Avires should be attached to th^ iron rods so as to 
hold them in place. The parallel rods may be placed 
at such distances from each other as will be most con- 
venient for the work in hand. 

Mortar Beds are made of rough lumber of any kind, 
and should be built partly in the ground, where cir- 
cumstances will permit. They require to be strongly 
put together, as they have considerable weight to sus- 
tain. The writer has seen mortar beds built up with 
bricks and cement where large works have been under 
construction. Sometimes, master workmen, who do a 
large business, and who employ a great number of men, 
keep a large mortar bed or two in the rear yard of 
their shop and tool house, in which they keep always 
en hand a supply of ready-made stuff, which enables 
them to do small jobs or repairs at a moment's notice. 

The Slack Box. — This is generally made of boards, 
and is eight or nine feet long, and from two to four 
feet wide, and twelve or sixteen inches in depth. An 
opening about eight inches square is left in one end, 
with a slide door attached, so that it can be opened or 
closed at pleasure. The opening should be covered on 
the inside with a grating, so that when the lime is run 
off no lumps or stones will get through. The grating 
may be made with iron rods, or may be formed with 
wooden laths or slats. The bottom of the box should 
be made as close and tight as rough boards will permit. 
(See No. 1, Fig. 11.) 

Lathing.\ — It frequently happens in towns and coun- 
try places that the plasterer has to do his own lathing, 
or at least have it done under his own supervision, 
therefore it will be necessary to have something to say 
on this subject, and on the tools employed by the work- 
man whose duty it is to prepare the walls for the plas- 



58 CEMENTS AND CONCRETES 

terer. These tools need not be extravagant ones or 
many in number. They consist of the following: 

Lathe7^'s Hatchet. — This is a small hatchet with a 
blade not more than one and a half inches wide, and 
rather larger in proportion than ordinary hatchets. 
The opposite end to the cutting edge is a hammer, with 
which the lather drives the nails. Sometimes the face 
of the hammer end is grooved, which makes it cling to 
the nails if the latter are not struck fairly on the head. 
An expert lather, however, will prefer a flat hammer 
face for driving lath nails. The cutting edge is used 
for "nipping" off laths when they are too long, or 
V7hen short spaces of lathing are required to be made. 
In cutting lath with the hatchet, the workman gives the 
wood a short sharp blow with the tool at the point 
where the severance is required, and the lath is in- 
variably cut at the first blow, if the operator is an ex- 
pert. (See 0, Fig. 2.) 

Nail Pocket. — Perhaps the best nail pocket a lather 
can have is made from a portion of an old boot leg cut 
off to about four inches deep, and having a bottom of 
semi-circular shape made of wood, and to which the 
portion of the boot is fastened by means of broad-head- 
ed tacks. The pocket is fastened to the workman's 
waist by means of a strap, or other suitable device, and 
hangs in front of him in a convenient position. Some- 
times nail pockets are made of canvas, but these are 
not so handy, as the top is apt to close and then nails 
are difficult to get at. This never occurs with the boot 
leg pocket. 

Cut-off Saw. — A cross-cut saw is an indispensable 
tool to the lather for cutting lath in larger quantities 
for short spaces, and for rigging up platforms to work 
on, and for cutting supplementary studding or strips 



TOOLS AND APPLIANCES 59 

where such are necessary. The saw should have rather 
coarse teeth and have plenty of set. Usually, the lather 
thinks that almost any old used-up saw is good enough 
for this purpose, and we find him struggling away with 
all his strength cutting through a bundle of lath, when, 
if he had a saw that was worth anything — as a saw — 
he would perform his labors with about one-half the 
effort, and one-third of the time. It is all wrong to 
think of being able to work satisfactorily with inferior 
>or imperfect tools. There is no economy in using tools 
of this kind, and any lather who fancies he is going 
to make or save anything by making use of an old 
buckled, mortar-stained saw, makes a terrible mistake. 
Get a good saw and keep it in good order, and it will 
pay you in two weeks. (See X, Fig. 2.) Besides these 
enumerated, there are many other tools and appliances 
that the plasterer will require, such as jointing rules, 
moulding knives, modelling tools, drags, chisels, com- 
passes, plumb rules, etc. * 



PLASTER, LIME, CEMENTS, SAND, ETC. 

Plaster of Paris. — Gypsum, from which plaster of 
Paris is made, is a sulphate of lime, and is so named 
from two Greek words — ge, the earth; and epsun, to 
concoct, i. e., concocted in the earth. In Italy it is 
known by the name of gesso; in Scotland it is called 
stucco; in this country it is known as calcined plaster; 
and in the English trade as plaster. The term "plas- 
ter" will henceforth be used in this book. The writings 
of Theophrastus and other Greek authors prove that 
the use of plaster was known to them. A stone, called 
by Theophrastus gypsos, chiefly obtained from Syria, 
was used by the ancients for converting into plaster. 
Gypsum is mentioned by Pliny as having been used by 
the ancient artists, and Strabo states that the walls of 
Tyre were set in gypsum. The Greeks distinguished 
two kinds — the pulverulent and the compact. The lat- 
ter was obtained in lumps, which were burnt in the fur- 
naces, and then reduced to plaster, which was used for 
buildings and making casts. 

Gypsum is found in most countries — Italy, Switzer- 
land, France, Sicily, The United States, and some of 
the South American States; also in Newfoundland and 
Canada. The latter is said to be the finest deposits in 
the world. It is found in England in many places. 
The finest gypsum is called "alabaster," and is soft, 
pure in color, and fragile. This white translucent ma- 
terial is a compact mass of crystalline grains, and is used 
for making small statuary, vases, and other ornaments. 
Gypsum is found in immense quantities in the tertiary 

60 



PLASTER, LIME, ETC. 61 

strata of Montmartre, near Paris. This gypsum usual- 
ly contains 10 per cent, of carbonate of calcium, not al- 
ways in intimate union with the sulphate, but inter- 
spersed in grains. This sulphate gives the Paris plas- 
ter some of its most useful properties. Pantin, near 
Paris, has large beds of gypsum, one bed being hori- 
zontal and over 37 ft. thick. 

The term '^ plaster of Paris" was mainly applied to 
it because gypsum is found in large quantities in the 
tertiary deposits of the Paris basin. Another reason 
is that lime and hair mortar is seldom used in Paris for 
plaster work, plaster of Paris being used for most kinds 
of internal and external work. Plaster is known in the 
color trade as terra alba. Plaster of Paris was known 
in England by the same name as early as the beginnings 
of the thirteenth century. The gypsum, in blocks, was 
taken from France, and burnt and ground there. It 
continued to be burnt and ground by the users until 
the middle of the nineteenth century. The burning 
was done in small ovens, and the grinding in a mill, 
sometimes worked by horse-power, or more often by 
hand. 

Plaster is the most vigorous as it is the oldest vehicle 
for carrying down generation after generation the mas- 
terpieces of art with which the golden age of sculpture 
enriched the human race. For reproductive uses, plas- 
ter enables youth to contemplate antiquity in its noblest 
achievements. Today plaster is revolutionizing indus- 
trial art for us, and in all probability for those who 
are to come after us. Plaster, lowly and cheap, but 
docile and durable, is the connecting agent with this 
greatest of men's endorsement in the past. Plaster 
thus employed in duplicating works of marble, pottery, 
and metal work, is today extending the finest indus- 



62 CEMENTS AND CONCRETES 

tries, modern and ancient. Plaster is one of the best 
known fire-resisting materials for building purposes. 
After the conflagration at Paris, it was found the beams 
and columns of wood which had been plastered were 
entirely protected from fire. In cases where limestone 
walls had been ruined on the outside by the flames pass- 
ing through the window openings, the same walls in- 
ternally escaped almost unscathed owing to their being 
protected with plaster. Plaster in some climates has 
great lasting properties. The Egyptians covered their 
granite sometimes, and sand stone always, with a thin 
coating of stucco. The Greeks coated even their mar- 
ble temples with plaster, and the plaster portions are 
now in better preservation than unprotected masonry, 
particularly at Agrigentum in Sicily. 

Quick and Slow Setting Plaster. — M. Landrin, in giv- 
ing the results of his long continued studies relative 
to the different qualities of gypsum, states that the 
more or less rapid setting of plaster is due to the mode 
in which it is burned. Its properties are very different 
when prepared in lumps or in powder. The former 
when mixed in its own weight of water sets in five min- 
utes, while the latter under similar conditions takes fif- 
teen minutes. The reason probably is that plaster in 
powder is more uniformly burned than when it is in 
lumps, which tends to prove this fact, that when the 
latter is exposed longer than usual to the action of heat 
it sets more slowly. Gypsum prepared at a high tem- 
perature loses more and more of its affinity for water, 
retaining, however, its property of absorbing its water 
of crystallization. Plaster heated to redness and mixed 
in the ordinary manner will no longer set; but if, in- 
stead of applying a large quantity of water, the small- 
est possible portion is used (say one-third of its 



PLASTER, LIME, ETC. 63 

Tveight), it will set in ten or twelve hours, and becomes 
extremely hard. To prepare good plaster^ it should not 
be burned too quick to drive off all its moisture, and 
for its molecules to lose a part of their affinity for the 
water. If the plaster is exposed to heat until it has 
only lost 7 or 8 per cent, of its moisture it is useless, 
as it sets almost immediately. If, however, the burning 
is again resumed, the substance soon loses its moisture, 
and if then exposed to the air it very rapidly retakes 
its water of crystallization, and absorption continues 
more slowly. It then sets slow^ly, but attains great 
hardness. 

Testing. — The quality of plaster may be tested by 
simply squeezing it with the hand. If it cohere slight- 
ly, and keeps in position after the hand has been gently 
opened, it is good; but if it falls to pieces immediately 
it has been injured by damp. Although plaster does 
not chemically combine with more than one-fourth of 
its VN^eight of water, yet it is capable of forming a much 
larger quantity into a solid mass, the particles of plas- 
ter being converted into a network of crystals, mechan- 
ically enclosing the remainder of the water. Sulphate 
of lime (plaster) is soluble in water to the extent of 1 
part in about 450, the solubility being but little influ- 
enced by temperature. It is on account of this solu- 
bility in water that cements which have to a large ex- 
tent plaster for their bases are incapable in this raw 
state of bearing exposure to the weather. The setting 
of plaster is due to hydration, or its having but little 
water to take up to resume a state of consolidation. 
Plaster is used with hydraulic limes to stop the slaking, 
and convert the lime into cement. These are then called 
*' selenitic." 

In 100 parts of gypsum there are 46 acid, lime 32, 



64 , CE:\rEXTS AND CONX'RETES 

and water 22 parts. Good plaster should not begin to 
set too soon, and it should remain for a considerable 
time in a creamy state. TThen once set it should be 
very hard. Plaster should set slowly, as it gives more 
time for manipulation, but principally because one 
which sets quickly and swells never becomes so hard 
as slow-setting material. The equality of plaster can- 
not be determined by its color, the color being regu- 
lated by that of the gypsum : but all things being equal, 
the whitest and hardest generally yields the best plas- 
ter. But as the exception proves the rule, it may be 
mentioned that some plasters (such as Howe's) are of 
a delicate pink tint, and of a very fine grain, and ex- 
ceedingly strong when gauged. This pink plaster is 
much appreciated by many plasterers for making origi- 
nals, as owing to its fineness and density it is very suit- 
able for cleaning or chasing up models taken from the 
clay, and also for durable moulding pieces. One of the 
whitest plasters known, which is also very close in tex- 
ture, is that manufactured by Cafferata. For cast work 
the color of plaster is of small moment, because the cast 
work is sooner or later colored with paint, and more- 
over, unfortunately daubed over with distemper, or 
worse still, ^uth whitewash. Coarse pla.sters are darker 
in color than fine. Coarse plasters of a sandy nature, 
and which rapidly sink to the bottom when put in 
water, contain too much silica, or improperly burnt 
g\^sum, or are derived from a bastard gypsum, and 
are generally of a weak nature. 

Compressive and Adhesive Strength. — The compres- 
sive resistance of properly baked plaster is about 120 
lbs. to the square inch when gauged with neat water 
and 160 lbs. when gauged with lime water ; thus show- 
ing that lime water hardens and improves the affinity 



PLASTER, LIME, ETU. 65 

of plaster. The adherence of plaster to itself is greater 
than to stone or brick. The adhesion to iron is from 
24 to 37 lbs. the square inch. 

French Plaster. — A considerable quantity of French 
plaster was formerly used in this country but our own 
is more uniform in quality and cheaper in price, so the 
use of the French material is somewhat limited. In 
Paris various kinds of gypsum mortars are in general 
use, raw gypsum and other materials being often inter- 
mixed. They also contain free carbonate of lime, ac- 
cording to the degree of heat to which the raw stone 
has been subjected. The Hotel de Platres, in Paris, 
affords a good illustration of the constructive uses to 
which plaster can be put, some of the blocks being 
about a hundred years old. 

Limes. — Lime is one of the most important materials 
in the building trades. Limestone is the general term 
by which all rocks are roughly classified which have 
carbonate of lime for their basis. They are obtained 
from many geological formations, varying in quality 
and chemical properties. The carboniferous consists 
of nearly pure carbonate of lime. In the limestone of 
the lias carbonate of lime is associated with silica and 
alumina (common clay), in proportions varying from 
10 to 20 per cent. Carbonate of lime is found in a state 
of chemical purity in rhombohedral crystals as Iceland 
spar. It is also found in six-sided prisms, known to 
mineralogists as arragonite. Its purest form as a rock 
is that of white marble. Colored marbles contain iron, 
manganese, etc. 

The lias strata consists of a thin layer of hard lime- 
stone separated by another of a more argillaceous char- 
acter, or shale, containing various proportions of car- 
bonate of lime. 



66 CEMENTS AND CONCRETES 

Hydraulic Lmies. — Hydraulic limes are those which 
have the property of setting under water or in damp 
X)laces, where they increase in hardness and insolubil- 
ity. The blue lias lime formation is that from which 
hydraulic lime is principally made. This lime^ while it 
has excellent hydraulic properties, can hardly be classed 
as a cement. The stones which produce these limes con- 
tain carbonate of lime, clay, and carbonate of mag- 
nesia. The clay plays an important part in giving hy- 
draulicity to the lime, consequently this power is great- 
er in proportion to the amount of clay contained in the 
lime. The proportion of clay varies from 10 to 30 per 
cent. When lime contains clay it is not so easily slaked 
as pure lime, and does not expand so much in doing 
so, and therefore does not shrink so much in setting. 

Lias lime (called blue lias from the color of the stone 
from which it is produced) is very variable in quality 
and is generally of a feeble nature, but is sometimes of 
an hydraulic nature. M. Vicat divides them into three 
classes : feebly hydraulic, ordinary hydraulic, and emi- 
nently hydraulic. "Those belonging to the first class 
contain from 5 to 12 per cent, of clay. The slaking 
action is accompanied by cracking and heat. They also 
expand considerably, and greatly resemble the fat limes 
during this process. They are generally of a buff color. 
Those of the second class contain from 15 to 20 per 
cent, of clay. They slake very sluggishly in an hour 
or so without much cracking or heat, and expand very 
little. They set firmly in a week. The eminently hy- 
draulic limes contain from 20 to 30 per cent, of clay, 
are very difficult to slake, and only do so after a long 
time. Very frequently they do not slake at all, being 
reduced to a powder by grinding. They set firmly in 
a few hours, and are very hard in a month. 



)} 



PLASTER, LIME, ETC. 67 

A natural hydraulic lime is obtained from what ap= 
pears to be a sedimentary limestone that has been 
formed by being deposited from water which held it in 
solution. It is very fine-grained, and contains almost 
no fossils, and scarcely the trace of a shell is to be seen, 
except at the top and bottoms of the divisions, which 
are four in number, and in all from 9 to 12 ft. thick. 
When first worked, the stone was slaked in hot kilnsi 
but now this is effected by grinding. According to the 
*'M'Ara" process, the *'lime shells" from the kiln are 
ground in the same way as the clinker of Portland ce- 
ment. Beginning with a stone-breaker, the lime passes 
from this to a pair of chilled crushing rollers, and final- 
ly to the millstones, after which the powder is carried 
by sere v-conveyor and elevator to a rotary screen, 12 ft. 
by 4 feet, covered with wire cloth, which retains and 
returns to the millstones any residue in excess of the 
required fineness. Sifting is a very important factor in 
the process, as it is scarcely possible to have the mill- 
stones so perfect that they will not pass a few large 
particles. 

The residue of imperfectly ground lime will doubt- 
less slake when mixed with water, but at long or un- 
certain periods, so that it is obvious that fine grinding 
is a necessity, and the setting properties are not fully 
and safely developed unless the whole is finely pulver- 
ized. With regard to ''Fat lime": the general prac- 
tice is for lime producers to show their lime as rich as 
possible by analysis, and for users to prefer a rich lime, 
for the reason that it makes a more plastic and better 
working mortar with the usual quantity of sand. Now, 
it has been proved by experiments, many and varied, 
and extending over a long period, by the most eminent 
authorities, French, German, English and American, 



68 CEMENTS AND CONCRETES 

that this preference should exactly be reversed, and 
that the poorer common limes will make the best mor- 
tar, and will, in a comparatively short time, show some 
light setting power, whereas the very rich limes never 
take band, except in so far as they return to their orig- 
inal condition of carbonate by the reabsorption of car- 
bonic acid from the atmosphere, and by the slow evap- 
oration of the water of mixture. If it does not evapo- 
rate, the mortar remains always soft. If it evaporates 
too quickly, the mortar falls to powder, a result which 
must be in every one's experience who has witnessed 
the taking down of old buildings, and the clouds of 
dust created by the removal of every stone. 

Some of the stones from which fat lime is produced 
contain a portion of sand as an impurity. They there- 
fore yield an inferior substance. This, though cheaper, 
is not so economical as pure lime, as it does not increase 
its volume so much when slaked. The pure or fat lime 
should only be used for plastering, as it is easily slaked, 
and therefore not so liable to blister as most hydraulic 
limes. It expands to double its bulk when slaked, and 
can be left and reworked again and again without in- 
juring it. 

The Romans are said to have prepared their limes. 
This ''lime putty," prepared by immersion for a longer 
or shorter period — seldom less than three weeks — before 
being used, is laid on in a very thin coat, and gives 
a hard skin to the surface. This hardness is largely, if 
not wholly, due to the fact that the lime is laid on in 
a thin layer on the floating coat that has already ab- 
sorbed carbonic acid from the air. This thin layer be- 
comes harder than the main body oi tke plaster. 

The whole process of preparing lime and laying 'J 
on the walls in thin coats, with a considerable space of 



PLASTER, LIME, ETC. 69 

time between the coating, is conducive to the ultimate 
hardness of the whole. The lime is first slaked, and 
then made into coarse stuff, and setting stuff, all this 
t'me being exposed to the carbonic acid of the atmos- 
phere. Again, each coat is long exposed to the same 
influence before being covered with the next, although 
in marked contrast to the system of using the mortar 
in building. 

Calcination. — The process of ''lime burning'' is car- 
ried out in several different ways. But whether the 
operation be carried out in the simplest manner, or in 
kilns constructed on the most scientific principles, it 
will still depend (both as regards the quality and quan- 
tity of lime produced) upon the kilnsman, as it is only 
by constant observation from day to day that the man 
becomes capable of judging whether the proper tem- 
perature has been reached or that a correct opinion 
can be formed as to the effects produced by the various 
disturbing causes which exert an important influence 
upon the working of a kiln, such as its size, shape, the 
quality of the fuel, and the state of the atm.osphere. 
The kilns vary in size and shape in different districts, 
though they are generally inverted cones or ellipsoids, 
into which layers of limestone and fuel are alternately 
thrown. When worked continuously as running kilns, 
the lime is periodically withdrawn from below, fresh 
quantities of fuel and stone being filled in at the top. 
When lime has not been properly calcined, or ''dead 
burnt," it will not slake with water. This may arise 
from two causes — from insufficient burning, when the 
limestone, instead of being entirely caustified, has only 
been changed into a basic carbonate, consisting of two 
equivalents of lime and one of carbonic acid, one-half 
only of its carbonic acid having been expelled. This 



70 CEiviENTS AND CONCRETES 

basic carbonate, on the addition of water, instead of 
forming a hydrate of lime, and being converted into 
a fine and impalpable powder, attended with the pro- 
duction of a large amount of heat, is changed, with 
little elevation of temperature, into a mixture of hy- 
drate and carbonate. In the case of hydraulic limes 
which contain a considerable amount of silica, this 
''dead burning" may arise from the limestone having 
been subjected to a too high temperature, whereby a 
partial fusion of the silicate of lime formed has been 
produced, giving an impervious coating to the inner 
portions of the stone, retarding the further evolution 
of the carbonic acid. On this account the eminently 
hydraulic limes require to be carefully calcined at as 
low a temperature as practicable ; and hence it is not 
infrequently found that lias lime has been imperfectly 
calcined. Pure limes, if subjected to an excessive 
temperature, exhibit somewhat less tendency to com- 
bine with w'ater than is the case with lime properly 
calcined. Caustic limes unite with water with great 
energy, so much so as to evolve a very considerable 
amount of heat. When water is poured upon a piece 
of well-burnt lime heat is rapidly generated, and the 
lime breaks up with a hissing, crackling noise, the 
whole mass being converted in a short time into a soft, 
impalpable powder, known as "slaked lime." 

Slaking. — Chemically speaking slaked lime is hydrate 
of lime — that is, lime chemicallv combined with a 
definite amount of water. In the process termed "slak- 
ing" one equivalent or combining proportion of lime 
unites with one equivalent of water, or in actual weight 
28 lbs. of lime combines with 91 lbs. of water (being 
nearly in the proportion of three to one) to form 37 
lbs. of solid hydrate of lime. The water loses its liquid 



PLASTER, LIME, ETC. 71 

condition, and it is to this solidification of water that 
the heat developed during the process of slaking is 
partly due. 

Slaking is a most important part in the process of 
making coarse stuff and putty lime. Unless the slak- 
ing is carefully and thoroughly done, the resultant ma- 
terials are liable to "blister" or "blow," owing to 
small particles still remaining in a caustic state. Blis- 
ters may not show until a considerable time has 
elapsed. There are three methods of slaking "lump- 
lime" — the first by immersion; the second by sprink- 
ling with water; and the third by allowing the lime to 
slake by absorbing the moisture of the atmosphere. 
Rich limes are capable of being slaked by immersion, 
and kept in a plastic state. They gain in strength by 
being kept under cover or water. Pliny states that the 
Romans had such great faith in this method that the 
ancient laws forbade the use of lime unless it had been 
kept for three years. All rich limes may be slaked 
b}^ mixing with a sufficient quantity of water, so as to 
reduce the whole to a thick paste. Lump lime should 
first be broken into small pieces, placed in layers of 
about six inches thick, and uniformly sprinkled with 
water through a pipe having a rose on one end, or by 
means of a large watering-can having also a rose, and 
covered quickly with sand. It should be left in this 
state for at least twenty-four hours before being turned 
over and passed through a riddle. The layer of sand 
retains the heat developed, and enables the process of 
slaking to be carried out slowly throughout the mass. 
Any unslaked lumps may be put into the middle of the 
next heap to be slaked. The quantity of water should 
be perfectly regulated, as if over-watered a useless paste 
is formed. If a sufficient quantity is not supplied, ^ 



iZ 



CEMENTS AND CONCRETES 



dangerous powdering lime is produced. Slaking by 
sprinkling and covering the lime lumps is frecpiently 
done in a very imperfect and partial manner, and por- 
tions of tlie lime continue to slake long after the mortar 
has been used. Special care must be exercised, and 
sufficient time must be allowed for the lime to slake 
when this method is employed. 

Different qualities of lime require variable amounts 
of water: but the medium quantity is about a gallon 
and a half to eveiw bushel of lime. No water should 
be added or the mass disturbed after slaking has be- 
g^un. In most places the lime for making coarse stuff 
is ffenerallv slaked bv immersion, and is run into 
a pit. the sides of which are usually made up with 
boards, brick work, or sand, the lime being put into 
a large tub containing water. When the lime is slaked, 
it is lifted out by means of a pail, and poured through 
a coarse sieve. It is sometimes made in a large oblong 
box. ha^ung a movable or sliding grating at one end to 
allow the lime to run out and also to prevent the sedi- 
ment from passing through. 

In preparing lime for plaster work, the general prac- 
tice is to slake it for three weeks before using. Not 
only so. but a particular cool lime is selected, for the 
reason that it is not liable to blister and deface the 
internal walls Avhen finished. Now. while all this pre- 
caution is taken in regard to plastering, in making mor- 
tar for building the lime is slaked and made up at 
once, and it is frecjuently used within a day or two. 
But this is not all. Limes which are unsuitable for 
plaster work, kno^n as hot limes, and which, when 
plasterers are obliged to use_. must be slaked for a 
period of — not three weeks, but more — nearly three 
months before usiug, and ai^e then not quite safe from 



PLASTER, LIME, ETC. 73 

blistering", are the limes mostly Msed for building pur- 
poses. It will at once be seen that when mortars of 
these limes are used immediately, the unslaked par- 
ticles go on slal^ing for a long time, drying up the 
moisture, and leaving only a friable dust in the joints. 
This should help in understanding the old Roman law 
which enacted that lime should be slaked for three 
years before using. If three years should seem to us 
an absurd time, yet it may be justly said that at least 
three months are required to slake completely, and to 
develop fully the qualities of many of the common 
limes in everyday use. Major-General Gillmore, the 
eminent American specialist on the subject of Limes 
and Cement, mentions that in the south of Europe it 
is the custom to slake the lime the season before it is 
to be used. 

Mortar. — This is a term used for various admixtures 
of lime or cement, with or without sand. For plaster 
work it is usually composed of slaked lime, mixed with 
sand and hair, and is termed ''coarse stuff," and some- 
times "lime and hair," also ''lime." In Scotland the 
coarse stuff is generally obtained by slaking the lump 
lime (locally termed shells) with a combination of 
water sprinkling and absorption. The lime is placed in 
a ring of sand, in the proportion of one of lime to 
three of sand, and water is then thrown on in suffi- 
cient quantities to slake the greater portion. The whole 
is then covered up with the sand, and allowed to stand 
for a day; then turned over, and allowed to stand foi 
another day; afterwards it is put through a riddle to 
free it from lumps, and allowed to stand for six weeks 
(sometimes more) to further slake by absorption. It 
is next "soured" — that is, mixed with hair ready for 
use. Sometimes when soured the stuff is made up ia 



74 CEMENTS AND CONCRETES 

a large heap, and worked up again as required for 
use. This method makes a sound, reliable mortar. In 
some parts lime slaked as above is mixed with an equal 
part of run lime. This latter method makes the coarse 
stuff ''fatter" and works freer. All slaked limes have 
a greater affinity for water than the mechanically 
ground limes. 

Grinding is another process for making mortar or 
"lime," and if made with any kind of limestone is 
beneficial. It thoroughly mixes the material, increases 
the adhesion, acids to the density, and prevents blister- 
ing. AYhen there is a mortar-mill, either ground or 
lump lime can be used, and the coarse stuff may be 
made in the proportion of 1 part lime and 3 parts 
sand. The lime sho aJo be left in the mill until thor- 
oughly reduced and incorporated, but excessive grind- 
ing is detrimental The process should not be con- 
tinued more than thirty minutes. Both material and 
strength is economized if lump lime is slaked before 
being put in the mill. 

"When a mortar-mill is used for grinding the lime, 
the sand may be partly or wholly dispensed with, and 
excellent results are obtained by using old broken bricks 
(clean and well burnt), stone chippings, furnace cin- 
ders (free from coal), or slag. It is most essential in 
all cases that the materials used should be perfectly 
clean. It should be "Borne in mind that a complete in- 
corporation of the ingredients is essential in the slak- 
ing and mixing for coarse stuff, whether done by hand 
or machine. The sand or other material used can be 
tested by washing a portion in a basin of clean water, 
then sifting through a fine sieve. If there is an undue 
residue of clav, fine dust or mud in the water or sieve, 
the whole of the ag-greofate should be washed or re- 



TSTS-' 



PLASTER, LIME, ETC. 75 

jected. Lias lime should be mixed dry with sand and 
damped down for seven or ten days to ensure slaking. 
It should not be used fresh for floating or rendering. 
Pure or rich limes are not so well adapted for outside 
work, or places exposed to the action of damp, as hy- 
draulic limes. Mortar should be well tempered before 
using. Pliny states that it was an ancient practice to 
beat the mortar for a long time with a heavy pestle 
just before being used, the effect of which would be 
not only more thoroughly to mix the materials, but to 
take from the outside of the sand the compound of 
lime and silica (if such had been formed during the 
period of seasoning) and by incorporating it with the 
mass, dispose it more rapidly to consolidate. Smeaton 
found that well-beaten mortar set sooner and became 
harder than mortar made in the usual wa.y. Mortar 
made from hydraulic limes should be mixed as rapidly 
as is compatible with the thorough incorporation of the 
materials, and used as soon as practicable after mixing, 
because if put aside for any length of time its setting 
properties will deteriorate. 

Pure limes may be rendered hydraulic by mixing 
them with calcareous clays or shales, which have been 
so altered by the agency of heat that the silica they con- 
tain has to some extent assumed the nature of soluble 
silica. In good coarse stuff each granule of sand is 
coated over with the lime-paste so as to fill the inter- 
stices; the lime-paster is to hold the granular sub- 
stances in a concrete form. If too much lime-plaster 
is present, it is called ''too fat"; if the lime-paster is 
deficient it is ''too lean" or "poor." This can be 
tested by taking up a portion on a trowel; the "fat" 
will cling to the trowel while the "lean" wil] run off 
like wet sand. The coarse stuff can be tested by mak- 



76 ■ CEMENTS AND CONCRETES 

ing briquettes and slowly drying; the good will stand 
a great pressure, whereas the bad will not — in some 
cases falling to pieces. Some coarse stuff will appear 
*'fat" on the trowel^ but it may be the fatness of mud, 
not the fatness of lime^ because sometimes sand is 
adulterated with fine-screened earth. When this stuff 
is made in the form of briquettes and dried, it will be 
extremely friable and easy to crush; or if put into 
water until soft, the earthy matter can be seen. Fine- 
screened earth, when dry and in bulk, does not seem 
an objectionable material; but in a wet state it is dirt 
or mud, and should at once be sent off to the works. 
All limes increase in strength by the addition of sand, 
being the reverse of Portland cement, which is weak- 
ened by this addition. Mr. Read made four samples 
of mortar with the proportions of ground lime and sand 
as follows: '' Ground lime mixed with 4, 6, 8 and 10 
parts of clean washed sand to 1 part of ground lime 
respectively. All set and went hard. One of each 
was placed in water; that made with 4 parts of sand 
expanded and went to pieces; those with 6, 8 and 10 
parts of sand remained whole, and continued to get 
harder." The addition of a small proportion of brick 
dust to mortar will harden and prevent the disinte- 
gration of mortar. The proportions are 1 part of brick 
dust, 2 parts of sand and 1 part of lime, mixed dry 
and tempered in the usual way. 

Adhesive Strength. — The adhesive strength of mortar 
varies according to the amount of sand used. The 
more sand used in the mortar, the less its adhesion. 
The following table shows the force required to tear 
apart bricks bedded in mortar made with the usual 
proportions of sand at the end of twenty-eight days: 



PLASTER, LIME, ETC. 



77 



Adhesive Strengths 


OF Limes and Cements. 


Fat lime and sand 




(1 to 3) 


4% lbs. 


per 


Sq. In. 


Common lias lime and 


sand 


(( 


9 " 


(( 


(( << 


(( (( (( (( 


(( 


(1 to 4) 


6% " 


(( 


(( (( 


Portland cement " 


(( 


(1 to 4) 


23 " 


(( 


<( (( 


(i (( (( 


(( 


(1 to 6) 


15% " 


(( 


(( (( 



The old mortar which was held in such high esteem- 
by the Eomans is said to have consisted of lime mixed 
with puzzolana or trass. Trass is a material similar 
in its nature to puzzolana, obtained from extinct vol- 
canoes in the valley of the Rhine, also in Holland, and 
is largely employed in engineering works. The name 
trass is derived from a Dutch word meaning a binding 
substance. Much has been written and said about the 
ancient and the old Roman mortars, but it may be 
safely said that, from the year one up to the present 
time, no cement or mortar has the strength, or could 
excel, or stand our variable climate as well as Portland 
cement. The primary cause of the premature decaj* 
which takes place in stuccos and cements, when used 
externally as a coating to walls, is the presence of 
muddy earth and decayed animal and vegetable matter 
in the sand used in the lime and cement. To this may 
be added the frequent impurities in the limes and ce, 
ment themselves. The impurities in the sand may be 
eradicated by a thorough washing, and the lime should 
be carefully selected, prepared and manipulated. Hav- 
ing now briefly reviewed the principal parts and 
process of mortar, the practical conclusions to be 
drawn are, that the quality of the lime is of as great 
importance as the quantity, and thorough slaking is 
imperative ; that the proportions of sand may vary con- 



78 CEMENTS AND COXCRETES 

siderably. and that it should be coarse and irregular in 
size, and of a clean and hard nature. 

The Hardening of Mortar. — According to the results 
obtained from tests and experience, the hardening of 
mortar is due to several causes acting collectively. 
These causes appear to be absorption of carbonic acid 
from the atmosphere, and the combination of part of 
the water with the lime which act upon the sand, dis- 
solve and unite with some of the silica of the sand is 
composed, thus forming a calcium silicate (silicate of 
lime). Some authorities state that the silicate of lime 
is formed by the reaction of lime and silicate of mor- 
tar, and to this is due the hardness of old mortar. In 
mortar from the pure lime, the initial setting is due 
to the evaporation of water, and to the production of 
minute crvstals of hvdrate of lime, which slowiv ab- 
sorbs carbonic gas from the air, the rapidity of this 
absorption necessarily decreasing in proportion to the 
difficulties presented to the free access of air. The 
setting and hardenins' of hvdraulic limes are due mainlv 
to crystallization brought by the action of water on 
the silicate of lime and not mere absorption of carbonic 
gas from the atmosphere, as is the case of fat limes. 

The Romans were convinced that it was owing to 
prolonged and thorough slaking that their works be- 
came so hard, and were not defaced bv cracks. Al- 
berti mentions that he once discovered in an old trough 
some lime which had been left there five hundred 
years, as he was led to believe by many indications 
around it, and that the lime was as soft and as fit to 
be used as if it had been recently made. Common mor- 
tar made of rich lime hardens very slowly, and only 
by the evaporation of the water of the mixture, and by 
the absorption of carbonic acid from the atmosphere, 



PLASTER, LIME, ETC. 79 

with which it forms a crystalline carbonate of lime. 
This process, however, is so slow, that it gave rise to 
the French proverb that "Lime at a hundred years old 
is still a baby"; and there is a similar proverb among 
Scotch masons, "When a hundred years are past and 
gane, then gude mortar turns into stane." Mortar 
from the interior of the pyramids, where it has been ex- 
posed to the action of the air, still contains free lime, 
although it is five thousand years old. It has been 
ascertained that in rich lime mortars the carbonic acid 
penetrates about one-tenth of an inch into the joint in 
the first year, forming a skin or film which opposes the 
further absorption of carbonic acid, except at a decreas- 
ing ratio, so that the lime remains soft for an indefi- 
nite period. In illustration of this several cases have 
been cited, amongst others one by General Treussart, 
who, in the year 1822, had occasion to remove oiie of 
the bastions erected by Vauban in 1666. After these 156 
years the lime in the interior was found to be quite 
soft. Dr. John, of Berlin, mentions that in removing 
a pillar of 9 ft. diameter in the Church of Saint Peter, 
Berlin, eighty years after erection, the mortar was found 
to be quite soft in the interior. 

General Pasley mentions several instances at Dover 
Harbor, and at Chatham dock yard, the latter in par- 
ticular, when part of the old wall was pulled down in 
the winter of 1834. The workmen were obliged to blast 
the brickwork fronting the river, which had been built 
with Roman cement, but the backing, done with common 
lime mortar, was in a state of pulp; the lime used had 
been prepared from pure limestone or chalk. But it 
is unnecessary to go back so far for knowledge of the 
absence of the setting quality in the rich limes, as 
there have been frequent experiences of it in the pres- 



80 CEMENTS AND CONCRETES 

ent age. While these remarks are true of the richer 
limes, many of our limes are comparatively poor in 
carbonate, and associated with silica, alumina, mag- 
nesia and oxide of iron, which may either be partially 
combined in the natural state, or enter into combina- 
tion with the lime during the process of calcination, 
and these limes might be termed slightly hydraulic. 

M. Landrin, who submitted tO' the French Academy 
the results of some experiments on the hydraulicity and 
hardening of cements and lime, came to the conclusion 
that (1) silicates of lime raised to high temperature 
set with difficulty, and in any case do not harden in 
water; (2) for the recalcination of cements to exert 
a maximum influence on the setting, in connection with 
water of the compound obtained, the process must be 
carried sufficiently far for the limes to act on the silica 
so as to transform it into hydraulic, and not fused 
silica; and (3) carbonic acid is an indispensable factor 
in the setting of siliceous cements, in as much as it is 
this substance which ultimately brings about their hard- 
ening. The comparative strengths of various mortars 
are shown in the following table: 



PLASTER, LIME, ETC. 



81 



-s 




<D 




a. 




a» 




O 




'Ti 




^ 




c3 




1— 1 




4-9 




f-^ 




.o 




PL, 


• 


O 
1— 1 


i 


03 






Q 


;h 


^ 


S 


w 


-M 




U 




o 




g 


^ 




-M 


•4-3 


^ 


fl 


o 


§ 


g 


o 


^73 


O 


fl 




oj 


TJ 




H S 


a 




•rH 


9 "^ 


h^^ 


H (1, 


O 


^ 
rt 


S 


cC 


• 1— 1 




-M 






3 


c« 




C]J 


Rt» 


rd 


?> 


+3 


?-( 




O 


5 




• 1— 1 


en 


>- 


o 


r- 


bjo 




fl 


O 



a> 
•I— I 

c6 

a 

o 









> • kit I • 


bjo 






V. g 9 •" a 


3 






•r-l ^ .,-1 


. TJ 






-M r- ( "^ -M <— < 








5 bJO g 5 biO 




• 


en 

I— ( 




^ a 


J3 Vh <1J ^ Vh 


a V. 


a 


7j O ^ 7j O 
5-3 +J (U C 


03 a; 


M 


a H 


o^ 

r— ( 4-** 




<^ 


•^■T:! IH •'-'r^ 


Gj 




HO 


^ cr -.5 ^ cr 


'T3 


slls 


• • 


tH T-H -r-l 

• • • • 


tH rH rH 


oosfc^ 




.000 


O o 


.2 Q.ot. 




• . • ^ ^ ,,.1 


4-> -t-> -M 


Ilsl 


• • 


• • '010-* 


OOiO b- 


• • 


• • • t- 00 00 


lO lO lO 


o.- 




odd 


d d d 


00 '^ 2 




•>— 1 rH 1— 1 tH T— 1 T-H 


tH r-f -rH 


• • 


• O O O O 


O O 


• • 


. .4_l 4-1 4.J 4^ .|_l -M 


4-> -4-» -(-1 


Rati( 
comp 
with : 

Mor 


• # 


. tH CD CO O O ^ 


T^ ^ l:- 


• • 


00 00 CO O CD tH 
(75 tH* t-H* C3 tH t— I 


coo £- 
tH tH d 


^- X3 










CO OS 


^ OiO CO t-'^Tj^ 


O CO CD 


eaki: 
ight 
areii 
n lbs 


rH O 


T^l t' 00 tH T^ 05 CO 

d co" 00* d CO 00 ci 


00 ^_ CO 

d 00 oo' 


(M^ 


CO O CO to t- iO ''^ 


CD CO (M 


M ^ p.r.. 




•I— 1 




^^^ 








c o ssS 


CO t- 


O CO O 00 T-i(M t- 


O 00 o 


.1^ 3"^ 


o o 


O O 00 00 CO CD C3 


00^ lO 


OS'S tc"'^ 






• • • 


T-1 z6 


C^ CO Tt< C<? »0 C5 lO 


CD CD '^ 


CO o 


00 CO lO tH CD CO OS 


CO 00 CO 


i:-^^ c3 


tH 


(M TH T-H tH T— ( 


T-l 


pqa^^.J 










u 










<x> 


CO CO 


CO lO CO o o o o 


O CO o 




c3 


CO CO 


CO W CD O lO O O 


o coo 


• 

cc 


^ 


tH t-H 


tH -r-i rH (M* tH ci Ccf 


■rH tA C*' 


a; 


o o 


O • • 'O CD CO 


a o CO CO 


;?; 


s 


o o 


O . . . lO CD 00 


C8 lO COOO 


o 

g 


3 


t-i T^ 


tH • • ' c> c> <z> 


^ ^"^^ 






. o oo o o o 


o o o 


o 


a 


• • 


. o o o o o o 


o o o 


PM 


0) 

Q 


• • 


• ^H ^^ ^^ ^^ ^M ^^ 


■i-H r-i r-i 




o o 


O Q O O O O O 


o o o 




o o 


o o o o o o o 


O o o 




OS 


(M(?i 


d d oo' d d 00 d 


d 00 d 




CO 




tH rH 


rH 


"3 


t- 1- 


t- lO O lO O -<!f iC 


rH iO OS 


•2 O 01 


T-* (M 


C5 tH CCl CO i> i> 00 


CQ C;i rH 


6 






■ 


^ 


5 


tH (M 


CO tH « CO tH C5 CO 


r-lC5C0 1 



82 CEMENTS AND CONCRETES 

Magnesia in Mortars. — Magnesia plays an important 
part in the ''setting" of hydraulic limes as well as in 
Portland cement. Vicat, after many experiments, was 
led to recommend magnesia as a suitable ingredient of 
mortars to be immersed in the sea, stating that if it 
could be obtained at a cost that would admit its appli- 
cation to such purposes, the problem of making con- 
crete unalterable by sea water would be solved. Gen- 
eral Gillmore, speaking of the American lime and ce- 
ment deposits, says: ''Magnesia plays an important 
part in the 'setting' of mortars, derived from the ar- 
gillo-magnesian limestone such as those which furnish 
the Rosendale cements. The magnesia, like the lime, 
appears in the form of a carbonate. During calcination 
the carbonic acid is driven off, leaving protoxide of 
magnesia which comports itself like lime in the pres- 
ence of silica and alumina, by forming silicate of mag- 
nesia and aluminate of magnesia. These compounds 
become hydrated in the presence of water, and are 
pronounced by Vic at and Chatoney to furnish gangues, 
which resist the dissolving action of sea water better 
than the silicate and aluminate of lime. This statement 
?s doubtless correct, for we know that all of these com- 
pounds, whether in air or water, absorb carbonic acid, 
and pass to the condition of subcarbonates, and that 
the carbonate of lime is more soluble in water holding 
carbonic acid and certain organic acids of the soil in 
solution than the carbonate of magnesia. At all e\ajts, . 
whatever may be the cause of the superiority, it is 
pretty well established by experience that the cements 
derived from argillo-magnesian limestones furnish a 
durable cement for construction in the sea." 

In Marshal Vaillant's report to the French Academy 
of Sciences, from the Commission to which Chatoney 



PLASTER, LIME, ETC. 83 

and Rivot's paper was referred in 1856, this superiority 
of the magnesian hydrates is distinctly asserted. A few 
years ago the French Government Office of Civil En- 
gineers made a series of comparative tests on three sam- 
ples each of French, English and German cement, in 
which the results are given in favor of the German 
cement, which contains magnesia to the extent of 2.4 
per cent, against 0.26 in the English and 0.32 in the 
French, and summed up thus: "A great value partly 
due to the higher percentage of magnesia contained in 
it." Gillmore further says that magnesian limestone 
furnishes nearly all the hydraulic cement manufactured 
in the western part of the State of New York. At 
East Vienna it has been used for cement, and at Akron, 
Erie County, N. Y., a manufactory of some extent is in 
operation. Vicat says : ' ' Having analyzed several old 
mortars, with the view of discovering, if possible, to 
what their superior durability might be attributed, I 
found, in some excellent specimens of very old mortar, 
magnesia to exist in considerable proportions." The 
limestones, therefore, from which these mortars were 
prepared must have contained the silica and magnesia 
as constituent ingredients; and it is to be remembered 
that it is the presence of these substances which com- 
municates the property of hardening under water. Pro- 
fessor Scorgie says of carbonate of magnesia: ''Mag- 
nesium carbonate is a substance very similar to carbon- 
ate of lime; it loses its carbonic acid in burning, com- 
bines with silica, etc., and behaves generally in the 
same way; it does not slake, however, on being wetted, 
but combines with the water gradually and quietly sets 
to some extent in doing so. Magnesium carbonate com- 
bined with lime, reduces the energy of slaking, and in- 
creases that of the 'setting' process; w^hen other sub- 



84 CEMENTS AND CONCRETES 

stances are present, its behavior and combination with 
them are similar to these of lime. When carbonate of 
magnesia is present in sufficient quantity, say about 30 
per cent., it renders lime hydraulic independently of 
and in the absence of clay." Colonel Pasley also, by 
experiments, demonstrated that magnesium limestones 
are suitable for hydraulic mortars. 

The foregoing assertions that magnesium carbonate^ 
combined with lime, reduces the energy of slaking and 
increases that of the "setting" processes are satisfac- 
tory and conclusive. Many such evidences showing the 
value of magnesia in hydraulic mortars might be quoted, 
but perhaps these are sufficient. 

Effects of Salt and Frost in Mortar. — Few experi- 
ments have as yet been made to test the general effects 
of salt in mortars, though as a preventive of the effects 
of frost it has been tried with varying results. 

In some experiments, designed to ascertain the effect 
of frost upon hydraulic limes and cement gauged with 
and without addition of salt to the water, cubes of stone 
were joined together with cement mixed with water 
ranging from pure rainwater to water containing from 
2 to 8 per cent, of salt. Before the cement was set the 
blocks were exposed in air at a temperature varying 
from 20 to 32 degrees Fahr., after which they were 
kept for seven days in a warm room. At the end of 
this time the samples were examined. The cement 
made Avith water was quite crumbled, and had lost all its 
tenacity. The cement made Avith water containing 2 per 
cent, was in better condition, but could not be described 
as good ; while that containing 8 per cent, of salt had not 
suffered from its exposure to the lowest temperature 
available for the purpose of experiment. It is suggested 
as possible that the effect of the salt was merely to pre- 



PLASTER, LIME, ETC. 85 

vent the water in which it was dissolved from freezing at 
the temperature named, and so permitted the cement 
to set in the ordinary way. But it must be allowed 
that in practice, salt dissolved in the water for mixing 
mortar has been successfully used to resist the effect 
of frost. A solution of salt applied to new plastered 
walls in the event of a sudden frost will protect the 
work from injury. The addition of a small portion 
of sugar will improve its adhesion, and increase the 
frost-resisting powers. 

Salt takes up the vapors from the atmosphere, caus- 
ing the work to show efflorescence, and in some instances 
to flake, especially in external work. That some en- 
gineers believe there is virtue in salt water is beyond 
doubt, because salt water has been named in their speci- 
fications for the gauging of concrete. Salt in Portland 
cement seems to act somewhat differently; as regards 
efflorescence it shows more in this material than in lime 
mortar. Salt should not be used in Portland cement 
work that has to be subsequently painted. According to 
the results of tests of mortar used for the exterior 
l)rick facing of the Forth Bridge piers below water they 
show a good average tensile strength. One part of 
Portland cement and one part of sand were slightly 
ground together in a mill with salt water, and briquettes 
made from this gauge gave an average of 365 lbs. per 
square inch at one week, and 510 lbs. at five weeks after 
gauging. It would be interesting to note the condition 
of this mortar a century hence, time being the trying 
test for all mortars. 

A solution of commercial glycerine mixed with the 
setting stuff, or used as a wash on newly finished lime 
plaster work, is a good preventive of the evil effects of 
frost. Glycerine solution may also be used for the same 



86 CEMENTS AND CONCRETES 

purpose on new concrete paving. Strong sugar water 
mixed with coarse stuff has some power in resisting 
frost. The quantity depends upon the class of lime, 
but the average is about 8 lbs. of sugar to 1 cubic yard 
of coarse stuff or setting stuff. The sugar must be dis- 
solved in hot water and the stuff used as stiff' as pos- 
sible. 

Sugar Witli Cement. — Sugar or other saccharine mat- 
ter mixed with cement has been tried with varying 
success. It is well known that saccharine is used with 
mortars in India. According to some experiments made 
in this country, the results obtained were that the addi- 
tion of sugar or molasses delayed the setting of the 
mortar, the retardation being greater when molasses was 
used. When certain proportions were not exceeded, the 
strength of the mixture was that of the pure cement. 
Less than 2 per cent, of sugar must be added to Port- 
land cement, and less than 1 per cent, to Roman, other- 
wise the mortar will not hold together. The sugar ap- 
pears to have no chemical action on the other materials, 
crystals of it being easily detected on the broken sur- 
faces, the increased binding power of the cement 
brought about by the addition of sugar being due more 
to mechanical than chemical causes. In my own experi- 
ments with sugar added to Portland cement for cast- 
ing deep undercut ornament figures and animals out 
of gelatine moulds, the results at first were very irregu- 
lar, some casts attaining great hardness, while others 
crumbled to pieces. The time of setting also varied 
considerably. Three different brands of cement were 
used, and it was found that the cement containing the 
most lime required more sugar than the lowest limed 
cement, but the average is about 1% per cent, of added 
sugar. The sugar must be dissolved in the water used 



PLASTER, LIME, ETC. 87 

for gauging. The setting and ultimate hardness is also 
influenced by the atmosphere. The casts should be kept 
in a dry place until set and dry, before exposing them 
to damp or wet. Portland cement has a tendency (es- 
pecially if over limed) to ''fur" gelatine moulds, but 
the sugared cement leaves the moulds quite clean. 

In experiments by Austrian plasterers, mixtures of 
1 part of cement and 3 parts sand, and 10 per cent, of 
water, and of pure cement with as much water as was 
necessary to give the mass plasticity, were prepared. 
From 1 to 5 per cent, of powdered sugar was well mixed 
with the dry cement. The cement used was of inferior 
quality, the sand being ordinary building sand, and 
not the so-called ''normal" sand, which is of a superior 
quality. They were left to harden in a dry place, and 
not under water. For each series of samples made with 
sugar a comparative series without sugar was prepared, 
all the samples being made by the same man, under the 
same conditions and with the same care. The tenacity 
was ascertained by Kraft's cement-testing machine. The 
strength was far below that prescribed and generally 
obtained. It should be mentioned that the samples with 
sugar (especially those of pure cement) shoAved a strong 
tendency during the first twenty-four hours to combine 
intimately with the smooth china plate on which they 
were placed to swell, and the results of the trial showed 
that with mixtures of cement and sand, and by harden- 
ing in a dry place, the binding effect may be increased 
by the addition of sugar, which reached its maximum 
with from 3 to 4 per cent, of sugar added. With pure 
cement the binding effect was not much increased. If 
the sugar used for gauging had been dissolved, and not 
mixed dry, the results would have proved better. 



88 CEMENTS AND CONCRETES 

Sugar in Mortar. — Most writers have supposed that 
the "Old Roman Mortars" contained strong ale, wort, 
or other saccharine matter, and it is probable that the 
use of sugar with lime passed from India to Egypt and 
Rome, and that malt or other saccharine matter was 
used in their mortars. The addition of sugar to water 
enables it to take up about 14 times more lime than water 
by itself. The following is an extract from the Roorkee : 
' ' It is common in this country to mix a small quantity of 
the coarsest sugar, 'goor,' or 'Jaghery, ' as it is termed 
in India, with the water used for mixing up mortar. 
Where fat limes alone can be produced their bad quali- 
ties may in some degree be corrected by it, as its influence 
is very great in the first solidification of mortar. This is 
attributed to the fact that mortars made of shell lime 
have stood the action of the weather for centuries owing 
to this mixture of Jaghery in their composition. Experi- 
ments were made on bricks joined together by mortar 
consisting of 1 part of common shell lime to 1% of sand, 
1 lb. of Jaghery being mixed with each gallon of water. 
The bricks were left for 13 hours, and after that time 
the average breaking weight of the joints in 20 trails 
was 61/2 lbs. per square inch. In twenty-one specimens 
joined with the same mortar, but without the Jaghery, 
the breaking weight was 4i^ lbs. per square inch. ' ' 

The Madras plasterers make most beautiful plaster 
work, almost like enamelled tiles, the shell lime being 
mixed with Jaghery. The surface takes a fine polish 
and is as hard as marble, but it requires a good deal of 
patient manipulation. Dr. Compton has made some ex- 
periments with sugar gauged with cements and mortars, 
and says, ' ' That in medicine there are two kinds of lime- 
water, one the common lime-water, that can be got by 
mixing lime and water, and it is particularly noted 



PLASTER, LIME, ETC. 89 

tliat, add as much lime as you like, it is impossible to get 
water to dissolve more than half a grain of lime in one 
ounce, or about two teaspoonfuls of water. But by add- 
ing 2 parts of white sugar to 1 part of lime, there is a 
solution obtained which contains about 14^ times more 
lime in the same quantity of water. Here it is to be ob- 
served — and it is a most important point — that there are 
hot limes, such as Buxton^ which if they be incautiously 
mixed with them, will burn the sugar, make it a deep 
brown color, and convert it into other chemical forms, 
and possibly destroy its value in mortar." 

The Jaghery sugar used in India is sold in the London 
market at about a penny a pound. Treacle seems to be 
the most promising form of saccharine matter; beetroot 
sugar is not good for limes or cements. There is a rough 
unrefined treacle which is very cheap, and it is supposed 
would have an excellent effect. 

Herzfeld states that he used coarse stuff, consisting of 
1 part of lime to 3 of sand, lo which about 2 per cent, 
of sugar had been added, to plaster some walls in the 
new building of the Berlin Natural History Museum, 
and on the day following he found the lime plaster had 
hardened as if gauged with plaster. He also found it 
useful in joining bricks, and recommends the coarse stuff 
to be fresh made, and not with a great proportion of 
water; and states that good molasses will yield as good 
results as sugar. 

Lime Putty. — This material is prepared in a similar 
way to run lime intended for coarse stuff. It is run 
through a finer sieve into a box or pit. If the latter is 
used the interior should be plastered with coarse stuff to 
prevent leakage and keep the putty clean. For good 
work the best class of lump lime should be used. The 
putty should be allowed to stanx^ for at least three 



90 CEMENTS AND CONCRETES 

months before it is used. For common work the lump 
lime for making coarse stuff, putty and setting stuff is 
often run into one pit. The putty at the end farthest 
from the sieve, being the finest, is retained for putty and 
for making setting stuff, and the remainder, or coarser 
portion, being used for coarse stuff. In many instances 
the putty is left for months in an unprotected state dur- 
ing the progress of the building, which is wrong. It may 
be kept for an indefinite time without injury if protected 
from the atmosphere, and therefore it should be covered 
up to resist the action of the air, as it absorbs the car- 
bonic acid gas and thus becomes slightly carbonated and 
loses to a certain extent its causticit}^, and consequently 
its binding and hardening properties. 

Pliny states that the old Roman limes were kept in cov- 
ered pits. If a small portion is taken off the top of the 
putty it will be found not only dry, but scaly, short and 
inert ; whereas a portion taken from the middle, or up to 
the part carbonated, will be found to be of an oily and 
tenacious nature. A cute plasterer always selects the 
putty furthest from the sieve for mitring purposes, as it 
is the finest. 

Setting .Stuff. — This material is composed of lime 
putty and washed fine sharp sand. The proportion of 
sand varies according to the class of lime and kind of 
work, but the average is 3 parts of sand to 1 of putty. 
The various proportions are given where required for the 
different works. Setting stuff is used for finishing coat 
of lime plastering. It is generally made on a platform 
of scaffold boards, and sometimes in a bin. The putty 
and sand are thoroughly mixed together by aid of a 
larry. The sand should be sized by washing it through a 
sieve having a mesh of the desired size. In some districts 
it is made by pressing or beating the putty and sand 



PLASTER, LIME, ETC. 91 

through a "punching sieve" into a tub. Setting stuff is 
less liable to shrink and crack, and is improved generally 
if it is allowed to stand after being made until nearly 
hard, but not dry, and then ' ' knocked up " to the re- 
quired consistency with water (preferably lime-water) 
and the aid of a shovel and larry. While the stuff is 
firming by evaporation it should be covered up to protect 
it from dust and atmospheric influences. It should be 
used as soon as "knocked up." Setting stuff may be 
colored to any desired tint, and also mixed with various 
ingredients to obtain a brilliant and marble-like surface. 

Haired Putty Setting. — Haired putty was formerly 
used to a very considerable extent as a setting coat in 
districts where the local lime was of a strong or hydraulic 
nature, not very readily manipulated when mixed with 
sand, as used for setting stuff. This material is com- 
posed of fine lime putty and well-beaten white hair. The 
hair was thoroughly mixed with the putty to tougheii 
and prevent it from cracking. To such an extent was hair 
added that in some instances the setting coat when 
broken had the appearance of white felt. This class of 
setting stuff is now seldom used. 

Lime Water. — This water has many medicinal virtues, 
and is a simple and inexpensive remedy for cuts and 
bruises. Plasterers are generally healthy and free from 
any infectious diseases. This may be partly owing to 
their almost constant contact with lime. Lime water, 
used as a wash, will harden plaster casts. It is also used 
when scouring and trowelling setting stuff to harden the 
surface. 

Hair. — Hair is used in coarse stuff as a binding me- 
dium, and gives more cohesion and tenacity. It is usu- 
ally ox-hair (sometimes adulterated with the short hair 
of horses). Good hair should be long, strong and free 



92 CEMENTS AND CONCHETES 

from grease or other impurities. It is generally obtained 
in a dry state in bags or bundles. This dry hair should 
be well beaten with two laths to break up the lumps, as, 
unless the lumps are thoroughly broken so as to sepa- 
rate the hair they are only a waste, and worse than no 
hair at all^ since the lumps have no binding power and 
will cause a soft weak spot in the plaster when laid. 
Many failures of ceilings have been caused by the hair 
not being properly beaten and mixed. Human hair is 
sometimes used for jerry work. Goats' hair is often used 
here. Hair is usually obtained direct from the tanners' 
yard, fresh and in a wet state. This makes the best 
work, as it is much stronger and mixes freely. Hair 
should never be mixed with hot lime, and with no mor- 
tars until nearly ready for using, because wet or hot 
lime weakens the hair, more especially if dry. Coarse 
stuff for first coating on lath work requires more hair 
than for brick or stone work. When coarse stuff is made 
in a mill the hair should not be added until the stuff is 
ground, as excessive grinding injures it. 

Fibrous Suhstitutes for Hair. — ]\Ianila fiber as a sub- 
stitute for hair in plaster work has been the subject of 
experiments in this country. One of the most conclu- 
sive of these tests was made by four briquettes or plates 
of equal size, one containing manila hemp, a second sisal 
hemp, a third jute and a fourth goats' hair of the best 
quality. The ends of the plates were supported and 
weights suspended from the middle. The result showed 
that plaster mixed with goats' hair broke at 1441/^ 
lbs. weight, the jute at 145 lbs., the sisal at 150, and the 
manila at 195, in the latter case the hemp not breaking, 
but cracking, and though cracked in the center, the lower 
half of this plate, when it was suspended, held onto the 
upper half, the manila securing it fast. The three other 



PLASTEPt, LIME, ETC. 93 

plates were broken — that is, the two parts of each plate 
had severed entirely. Another experiment consisted in 
mixing two barrelfuls of mortar, each containing equal 
portions by measure of sharp sand and lime, one of the 
barrels, however, being mixed with a proper quantity by 
measure of manila hemp, cut in lengths of l^^ to 2 
inches, and the other of best goats ' hair. On being thor- 
oughly mixed with the usual quantity of water, the re- 
spective compounds were put in the barrels and stored 
away in a dry cellar, remaining unopened for nine 
months. On examination the hair mortar crumbled and 
broke apart, very little of the hair being visible, showing 
that the hair had been consumed by the action of the 
lime; but the other, containing the hemp, showed great 
cohesion. It required quite an effort to pull it apart, 
the hemp fiber permeating the mass and showing little 
or no evidence of any injury done to it by the lime. 

Sawdust as a Substitute for Hair. — Sawdust has been 
used as a substitute for hair, also for sand in mortar for 
wall plastering. It makes a cheap additional aggregate 
for coarse stuff. Sawdust mortar stands the effects of 
rough weather and frost when used for external plaster- 
ing. The sawdust should be used dry and put through a 
coarse sieve to exclude large particles. I have used it 
with plaster for both run and cast work. It proved use- 
ful for breaks of heavy cornices by rendering the work 
strong and light for handling. Some kinds require soak- 
ing or washing, otherwise they are liable to stain the 
plaster. Several patents have been issued in America for 
the use of sawdust in place of hair and of sand. One of 
these is for the use of equal parts of plaster, or lime and 
sawdust ; another is for the use of 4I/2 parts each slaked 
lime and sawdust to 1 part of plaster, 14 part of glue 
and 1-16 part of glycerine, with a small part of hair. 



91 CEMENTS AXD CONXRETES 

Kalil's patent plaster consists of 35 per cent, of saw- 
dust. 35 per cent, of sand. 10 per cent, of plaster, 10 per 
cent, of glue, and 10 per cent, of wliiting. 

Sand. — Sand is the most ^videlv distributed substance 
in nature, not only in the mineral but also in the animal 
and vegetable kingdoms. Clay contains no silica (the 
chemical name for sand). Sand is the siliceous x^articles 
of rocks containing quartz, production by the action of 
rain, wind, wave and frost. Some kinds of sand are also 
found inland: the deposits mark the sites of ancient 
beaches or river beds. Sand is classed under various 
heads, viz., calcareous, argillaceous and metallic. Sand 
varies in color according to the metallic oxides contained 
in them. Fcav substances are of more importance than 
sand for plastic purposes. Its quality is of primary im- 
portance for the production of good coarse stuff, set- 
ting stuff, and for gauging with Portland or other 
cements used for plaster work. Its function is to induce 
the mortar or cement to shrink uniformlv durina^ the 
process of setting, hardening or drying, irregular shrink- 
age being the general cause of cracking. Sand is also a 
factor in solidity and hardness; while being of itself 
cheaper and used in a larger proportion than lime or 
cement, it decreases the general cost of materials. There 
ai^e three kinds — pit, river and sea sands. They gen- 
erally ccmtain more or less impurities, such as loam, 
clay, earth and salts, necessitating their being well 
washed in water, more especially for the finishing coats 
of plaster or cement work. Pit sand is sometimes found 
quite clean; it is generally sharp and angular. River 
sand is fine grained, not so sharp as pit sand, but makes 
good setting stuff. Sea sand varies in sharpness and 
size, and for plastering it should be washed to free it 
from saline particles which cause efflorescence. 



PLASTER, LIME, ETC. 95 

Regarding the use of sand in mortars, it may almost 
be spoken of as a necessary evil. Sand is necessary to 
give body and hardness to an otherwise too soft and 
plastic material, and the coarser and cleaner the better, 
as the coarse particles allow the carbonic acid to pene- 
trate further into the body of the mortar, and assist in 
the hardening process for this reason. In the case of 
cements of all kinds sand is only good for lessening the 
cost of the aggregate, and in the case of the majority of 
sands in daily use in most places the strength is reduced 
out of all proportion to the saving effected. Brunei, in 
the Thames Tunnel, was so convinced of this that he used 
pure Portland cement in the arches; and General Pas- 
ley, treating of this, recommends that only pure cement 
should be used on all arduous works. 

As to the quality of sands, they are of very wide 
variety — so much so, that 1 part of an inferior or soft 
clayey sand will reduce the strength of mortar as much 
as 3 or 4 parts of clean sharp granitic sand. This is well 
exemplified in the sand test, which is made with what is 
called standard sand, being a pure silecious sand sifted 
through a sieve of 400 holes to the square inch and re- 
tained on one of 900. 

Good sand for lime plaster should be hard, sharp^ 
gritty and free from all organic matter. For coarse stuff 
and cement for floating coats it should not be too fine. 
Good sand for plaster work may be rubbed between the 
hands without soiling them. The presence of salt in sand 
and water is found not to impair the ultimate strength of 
most mortars; nevertheless it causes an efflorescence of 
white frothy blotches on plaster surfaces. It also ren- 
ders the mortar liable to retain moisture. 

Fine-grained sand is best for hydraulic lime; the 
coarse-grained is best for fat limes, and coarse stuffs and 



96 CEMENTS AND CONCRETES 

Portland cements for floating. Sand should not be uni- 
form in size, but, like the aggregate for concrete, should 
vary in size and form. A composition of fine and coarse 
sand for coarse stuff, unless the sand is naturally so 
mixed, gives the best results, for as the lime will receive 
more sand in that way without losing its plasticity it will 
make a harder and stronger material, whether coarse 
stuff, setting stuff or for Portland cement work. If there 
is plenty of fine sand and a scarcity of coarse sand, they 
should be mixed in the proportion of 2 of coarse to 1 of 
fine. If on the other hand, there is plenty of coarse 
sand and a scarcity of fine, they should be mixed in the 
proportions of 2 of fine to 1 of coarse. The proportion of 
sand varies according to the different kinds and qualities 
of limes and cements, also purposes. Baryte is some- 
times used as a substitute for sand. Silver sand is used 
for Portland cement work when a light color and a fine 
texture is required. 

Mastic. — Mastic was formerly extensively used foi 
various purposes in which now Portland cement is chiefly 
employed. It is still used sometimes for pointing the 
joint between the wocd frames of windows and the stone 
work. Mastic is waterproof, heat-resisting and adheres' 
to stone, brick, metal and glass with great tenacity. Mas- 
tic is made in various ways. Some plasterers make their 
own. 

Scotch Mastic is composed of 14 parts of white or 
yellow sandstone, 3 parts of whiting and 1 part of lith- 
arge. These are mixed on a hot plate to expel any mois- 
ture and then sifted to exclude any coarse particles. It 
is then gauged with raw and boiled linseed oil in the 
proportion of 2 of raw to 1 of boiled oil. The sandstone 
,is pounded or ground to a fine powdered state before 



PLASTER, LIME, ETC. 97 

bein^ mixed. The surface to be covered is first brushed 
with linseed oil. 

Common Mastic is prepared as follows : 100 parts of 
ground stone, 50 parts silver sand or of fine river sand, 
and 15 parts of litharge. These are all dried and mixed 
and passed through a fine sieve; it then resembles fine 
sa]id. This mastic may be kept for any length of time in 
a dry place. When required for use it is gauged with 
raw and boiled linseed oil (in equal proportions) until 
of the consistency of fine stuff. It requires long and fre- 
quent beating and kneading — in fact, the more it is 
knocked up the better it works. Its fitness for use can 
be ascertained by smoothing a portion of the gauge*with 
a trowel. If there are any separate parts of the differ- 
ent materials or bright spots seen the knoeking-up must 
be renewed until it is of even texture. The addition of 15 
parts of red lead is sometimes used to increase the tenac- 
ity of the mastic. 

Mastic Manipulation. — The walls are prepared for 
mastic by raking out the joints and sweeping with a 
coarse broom, and the brick work well saturated with lin- 
seed oil. Narrow screeds about 1 inch wide are formed in 
plaster to act as guides for floating the work plumb and 
level. When laying the mastic it must be firmly pressed 
on and the floating rule carefully passed over the sur- 
face until it is straight and flush. The screeds are next 
cut out and the spaces filled in with extra stiff mastic. 
The whole surface is then finished with a beech or syca- 
more hand float, leaving a close and uniform texture. 
Mastic moldings are first roughed out with Medina or 
other quick-setting cement. The running mold is muffled 
so as to allow i/4 inch for the mastic coat. 

Hamelein's Mastic. — This mastic consists of sand and 
pulverized stone, china, pottery, shard, to which are 



98 CEMENTS AND CONCRETES 

added different oxides of lead, as litharge, gray oxide 
and minium, all reduced to powder, to which again is 
added pulverized glass or flint stone, the whole being 
intimately incorporated with linseed oil. The propor- 
tions of the ingredients are as follows: To any given 
weight of sand or pulverized pottery ware add two-thirds 
of the weight of pulverized Portland, Bath or any other 
stone of the same nature. Then to every 550 lbs. of this 
mixture add 40 lbs. of litharge, 2 lbs. of pulverized glass 
or flint stones, 1 lb. of minium and 2 lbs. of gray oxide 
of lead. The whole must be thoroughly mixed together 
and sifted through a sieve, the fineness of which will de- 
pend on the different purposes for which the mastic is 
intended. The method of using is as follows : To every 
30 lbs. of the mastic add 1 quart of linseed oil and well 
mix together either by treading or with a trowel. As it 
soon begins to set, no more should be mixed at a time 
than is requisite for present use. Walls or other sur- 
faces to be plastered with this material must first be 
brushed with linseed oil. 

Mastic Cement. — Mix 60 parts of slaked lime, 35 parts 
of fine sand and 3 parts of litharge, and knead them to 
a stiff mass with 7 to 10 parts of old linseed oil. The 
whole mass must be well beaten and incorporated until 
thoroughly plastic. This mastic cement assumes a fine 
smooth surface by troweling. It is impervious to damp 
and is not affected by atmospheric changes. 



TERMS A^D PROCESSES. 

The following descriptions are suited to most locali- 
ties, though there are districts in the East and South 
that vary somewhat from the processes as described; 
the difference, however, is so trifling that the regular 
plasterer will have no trouble in reconciling such differ- 
ences. 

Three-Coat Work.t — Three-coat work is usually speci- 
fied by architects for all good buildings, but sometimes 
two-coat work is specified for inferior rooms, closets, at- 
tics or cellars in the same building. Three-coat work 
makes a straight, smooth, strong and sanitary surface for 
walls and ceilings when properly executed. The follow- 
ing is the process for three-coat work^ which consists of 
first-coating, floating and setting. 

First-Coating. — "First-coating" is termed in the 
United States "scratch-coating.'' It is executed by lay- 
ing and spreading a single coat of coarse stuff upon the 
walls and ceilings to form a foundation for the subse- 
quent floating and setting coats. Coarse stuff for first- 
coating should be uniformly mixed or ' ' knocked up, ' ' as 
commonly called. It should contain more hair than that 
used for floating, so as to obtain a strong binding key on 
the lath-work and form a firm foundation for the float- 
ing coat. Coarse stuff may be tested by lifting some 
from the heap on the point of a trowel. If it is suffi- 
ciently haired and properly mixed the stuff should cling 
to the trowel when held up and the hairs should not be 
more than 1-16 inch apart. It should be stiff enough to 
cling and hold up when laid, yet sufficiently soft and 

99 



100 CEMENTS AND CONCRETES 

plastic to go through the interstices between the laths. 
Unless the stuff is made to the proper consistency it will 
"drop" — that is, small patches where the excess water 
accumulates or at weak or too wide spaced laths will fall 
soon after being laid. 

When first-coating ceilings, the coarse stuff should be 
laid diagonally across the laths, a trowelful partly over- 
lapping the previous one, the one binding the other. By 
laying the stuff diagonally the laths yield less, present a 
firmer surface and are not so springy as when laid across 
or at right angles to them. Laying the stuff diagonally 
and overlapping each trowelful helps to retain the stuff 
in its place, which otherwise is apt to "drop." The stuff 
should be laid on with a full-sized laying trowel, using 
sufficient pressure to force it between the laths and to 
go sufficiently through to form a rivet and lap or clinch 
on the upper sides of the lathing. The stuff should be 
laid fair and as uniform in thickness as possible. The 
thickness should not exceed % inch or be less than % 
inch. If too thick it tends to weigh down the lath work 
and is apt to crack ; if too thin the subsequent scratching 
is liable to cut the coat down or nearly to the laths, thus 
leaving a series of small detached pats which are un- 
stable and form a weak foundation for the floating coat 
and are a source of cracks and often the cause of the 
w^ork falling when subjected to vibration. A thickness 
of y2 inch gives the best results. 

Scratching. — Scratching is sometimes termed "scor- 
ing," also "keying." It is done with a wooden or iron 
scratch, which may have from one to five points. 
Scratching is scoring the surface of the first coat to 
obtain a key for the following coat. The first-coating 
should be allowed to stand for an hour or two to allow 
the stuff to get firm before proceeding with the scratch- 



TERMS AND PROCESSES 101 

ing. If scratched while the stuff is soft it is apt to drop, 
and unless a man is careful and light in his working the 
scratch will go too deep and weaken the body and the 
rivets of first-coating. A wide scratch should be slightly 
angular at the points; if square, it should be drawn 
across the work in a slanting position so as to give an 
undercut key. The whole of the surface should be uni- 
formly scratched with a moderately sharp pointed 
scratch. The surface should be cross-scratched diag- 
onally. Square scratching cuts and weakens the rivets, 
especially when the scratch is drawn in the same line as 
the laths. Good work is generally scratched with a sin- 
gle lath. This, like other scratches, should be drawn in 
a slanting position, so as to give an undercut score. Sin- 
gle scratches is the best way for circular surfaces. First 
score it diagonally across the laths and then crossw^ys 
diagonally, keeping the scoring rather square than loz- 
enge-shaped. When too pointed the acute angles are 
liable to be broken when laying the floating coat. The 
scores should not be more than ly^ inch from center to 
center, or less than one inch from center to center. Close 
scoring weakens the body of the first-coating, while wide 
scoring affords insufficient key. Scratching with a single 
lath requires thrice or even more time than if done with 
a four or five pointed scratch, but the work is stronger, 
as the body and the rivets of the first coating arc; not 
cut too deep or otherwise weakened. In some instancies — 
such as a thin body of first-coating already mentioned — • 
the scoring is so deep that the body of the work is cut 
into a series of detached parts. By using a single lath 
or point the scoring is also more uniform and better un- 
dercut, thus obtaining a stronger surface and a better 
key for the floating coat. The additional time required 
for ''single scratching" should be taken into considera- 



102 CEMENTS AND CONCRETES 

tion, and annotated and allowed for when making speci- 
fications and estimating. All scratching should be done 
uniformly, taking care not to miss any parts, especially 
round door and window frames, wood grounds or where 
there may be jarring or vibration. On the regular and 
proper scratching depends the key and stability of the 
succeeding coats. Scratching with the point of a trowel 
should not be permitted. The use of a trowel as a 
scratch is detrimental to the strength of the stuff and the 
key. The sharp edge of the trowel cuts the hair and 
thus weakens the stuff. The smooth and thin plate of the 
trowel leaves a smooth and narrow key; the smooth side 
of the key presents no attachment for the second coat, 
while the deep part of the key is too narrow to receive 
its due portion of stuff to fill it up, thus leaving a space 
for contained air and a more or less hollow and unsound 
body. 

Rendering. — The first coat on brick, stone or concrete 
walls is called rendering. Before laying the coarse stuff 
the superfluous mortar in the joints of brick or stone 
walls should be cleared off, as the mortar used by brick- 
layers and stonebuilders often contains live or imper- 
fectly slaked lime, which in many instances is the cause 
of the plaster work blowing or scaling off. The walls, 
whether of brick, stone or concrete, should be well swept 
with a hard coarse broom and thoroughly wetted to cor- 
rect the suction, which otherwise would absorb the requi- 
site moisture from the coarse stuff, causing it to become 
inert and dry, consequently weak and non-adhesive. In 
some cases the joints of brick-work should be raked out 
and the face of stone walls roughened by picking. The 
coarse stuff for rendering walls does not require so much 
hair or to be used so stiff as for coating lathwork. First- 
coating or rendering is generally looked upon as a simple 



TERMS AND PROCESSES 103 

process, but it should be carefully laid and scratched, as 
it is the foundation for the other work. 

Floating. — Floating* or second-coating, termed '' brown- 
ing," is the laying of the second coat of coarse stuff on 
the first coat when dry to form a straight surface for the 
finishing coat. If the first coat has been standing for 
some time it should be well swept to clear off any dust 
that may have accumulated during the interval between 
the application of the coats. Where the coarse stuff is of 
a porous nature a damp brush should be passed lightly 
over the first coat as the work proceeds to prevent the 
moisture being sucked out of the second layer, which, if 
too dry, would tend to crack and fall away. The coarse 
stuff for floating should be used in a softer state than 
for first-coating, because when too stiff the extra press- 
ure required for laying is apt to crack the first coat on 
lath work. It also goes more freely and firmly into the 
recesses of the scratching. (It may be here mentioned 
that a mortar called ''dogga" is extensively used in 
South Africa for plaster and building work. Dogga is 
the ground dug up and tempered with sand, about 2 to 
1 for rendering and floating. Heavy ground requires 
more sand. Lime is very expensive in that country and 
is only used for the best class of work.) Floating for 
lime plastering consists of four parts: (1) Plumbing 
and levelling ' ' screeds ' ' to act as bearing for the floating 
rule and running mold; (2) flanking or filling in the 
spaces between the screeds; (3) scouring; (4) keying the 
surface. These parts are performed as follows: 

Screeds.^ — In good work the wall screeds are plumbed 
and the ceiling screeds levelled. Wall screeds are 
plumbed by forming *'dots" at the top and bottom of 
the internal and external wall angles. If there are wood 
grounds to receive wood skirtings they are used instead 



104 



CEMENTS AND CONCRETES 



6<^' 



.f»n 



NO. 3. 



of bottom dots. The dots are made by 
driving two nails through the first coat 
into the studs or joints of the wall, 
: allowing them to project about % inch 
^ft beyond the face of the first coat. The 
position of the top nail should be imme- 
diately beneath the cornice bracket. If 
there is no bracket the depth of the 
cornice should be allowed for. The 
bottom nail is placed in a liije with the 
upper member of the skirting molding. 
The nails should be pla(^ed perpendicu- 
lar with each other, otherwise the 
plumb-bobline will not work in unison 
with the gauges. The dots are plumbed 
by means of a plumb-rule. If the walls 
are too high for an ordinary sized 
plumb-rule to be used a chalkline, with 
a plumb-bob attached, and two wooden 
gauges will be required. Illustration 
No. 3 shows the nails, gauges and 
plumb-bobline in position. BB are the 
nails in the wall, one just below the 
cornice bracket and the other a little 
: above the floor line; AA are the gauges 
: with the line hanging fair with their 
shoulders, being the correct position 
B when the nails are plumb. The gauges 
: are generally cut out of a strong lath. 
• They must be made exactly to the same 
length. The plasterer at the top holds 
the end of one gauge on the top nail, 
with the chalk-line resting on the shoul- 
der, of the gauge, while the plasterer 



TERMS AND PROCESSES 105 

at the bottom holds the other gauge on the bot- 
tom nail Avith one hand and guides the plumb-bob 
with the other. The nails are now driven in as re- 
quired until they are plumb. Care must be taken to 
allow for a fair thickness for the floating coat. This 
should not be more than % inch or less than % inch. 
When working from a wood ground the top dots should 
be kept a little inside the plumb-line to allow for the 
traversing of the cornice screed, because this screed and 
the gathering at the bottom of the cornice are apt to 
throw the wall out of plumb unless cut off or allowed for. 
The dots are completed by laying narrow strips of 
gauged coarse stuff up to and in a vertical line with the 
top and bottom nails; the floating rule is then applied 
and the stuff worked down until flush with the nails. The 
dots should not be wider than the width of the floating 
rule, as the rule when bearing on the nails can only be 
worked with an up-and-down motion, taking in only its 
own width. The length of the dots may vary from 5 
to 7 inches, according to the bearings required for the 
cornice and skirting running mold. Narrow screeds are 
easier, quicker and truer made than wide screeds. The 
latter are apt to have a more or less wavy surface. This 
applies more especially to '4aid screeds" — that is 
screeds that are simply laid and ruled off without dots 
or other bearings. 

Lath dots are sometimes used instead of nail dots ; they 
are generally used on ceilings and lathed partitions ; they 
are not so liable to crack the first coat as nails. They 
are formed by laying a strip of coarse stuff and placing 
thereon a straight lath about 6 inches long and then 
applying a plumb-rule or plumb-bobline as described 
for the nail dots. The lath gives strength and resist- 
ance while working the floating rule. After the screeds 



106 CEMENTS AND CONCRETES 

are finished the laths are taken out and the spaces made 
good. Having finished all the top and bottom dots, the 
top and bottom longitudinal spaces in a line with the 
dots, or, in other words, the screeds are laid with coarse 
stuff. The long floating rule is then applied, bearing on 
the dots and working up and down in a slanting posi- 
tion, a plasterer working the rule at each end, and work- 
ing together so as to keep the rule square on edge and 
uniformly level. Any surplus stuff is taken off the rule 
and applied to make up any hollow parts in the screed 
or returned to the gauge board, as the case may be. If 
the screeds are extra long another man (sometimes more) 
is required to work at the center of the rule, also clean 
the surplus stuff off, and make up any deficiencies in the 
screed. After the screeds are finished, the nails must be 
extracted to avoid rust discoloring the finishing coat. 
Large surfaces on walls or ceilings should be divided in- 
to bays by narrow screeds placed from 6 to 9 feet apart. 
This affords more freedom and regularity for laying and 
ruling off. Gauged coarse stuff is sometimes used for 
the main screed, i. e., the wall and ceiling screeds on 
which the cornice is run. In this case the screeds are 
finished smooth, or so that they only require a very thin 
or filling-up coat of gauged putty for the cornice screeds. 
The splayed edges of screeds, especially gauged screeds, 
should be cut square. A splayed edge being generally 
smooth, affords little or no key, and also being unequal 
in thickness, makes a bad joint for the floating coat. 
If there are any breaks in the room, the screeds must be 
set off square from the side walls, and the projections 
at each angle of the breast made equal. The sides are 
best squared with a large wooden square, and the pro- 
jections regulated with a gauge. 
Flanking. — Flanking or filling in consists of laying 



TERMS AND PROCESSES 107 

the intervening spaces between the screeds with coarse 
stuff, and then ruling the surface straight and flush with 
the screeds, with a floating rule. Two squads of men, two 
or three in each squad, are required for this purpose — 
one squad on the floor, and the other on the scaffold. If 
the height of the room necessitates more than one scaf- 
fold, an additional squad is required for each interven- 
ing scaffold. In the latter case, the distance between the 
top and bottom screeds would be too great to allow a 
floating rule to be conveniently worked. To overcome this 
difficulty, intermediate screeds must be made at conven- 
ient distances. This is done by stretching a chalk-line 
from the top to the bottom screed, and then forming dots 
flush with the line, and laying the screeds as previously 
described. The coarse stuff for flanking should be laid 
upwards, and in an angular line. This plan is not so apt 
to spring the lath or crack the key at the deepest, which 
is the thinnest part of the first coat, as if laid across the 
laths. After a bay is laid, the surface is straightened 
with a floating rule. A plasterer at the top and one at 
the bottom works the rule together uniformly up and 
down with a cutting motion, and keeping it in a slightly 
angular position, so that any surplus stuff may not fall 
on the man below. A rule should not be worked on 
either of its face edges, as by so doing the face becomes 
round and uneven, and conducive of unequal screeds. 
The filling in and ruling off is continued until all the 
walls are completed. When elaborate ceilings have to be 
done, involving the expenditure of much time, the top 
longitudinal screeds are only formed, and the floating of 
the walls left until three or four days before the setting 
can be begun, as the setting coat made from some limes 
adheres better when the floating coat is partly green, or 
at least not bone dry. As previously mentioned, the 



108 CEMENTS AND CONCRETES 

whole process of preparing lime plaster and laying it on 
the walls in thin coats, with a considerable space of time 
between the coatings, is conducive to the ultimate hard- 
ness of the whole, the lime being first slaked and then 
scoured, all this time being exposed to the carbonic acid 
of the atmosphere. Again, each coat is long exposed to 
the same influence before being covered with the next, 
thus enabling each coat to harden by a natural process 
before the following coat is laid. All things being equal, 
it is advisable to allow each coat to stand as long as pos- 
sible before proceeding with the next. Where the wall 
surface is irregular, causing extra thick parts in the 
floating coat, the hollow parts should be rendered or 
"dubbed out," and the surface scratched before laying 
the floating coat. The dots for the ceiling screeds are 
formed <ilose to the cornice bracket. If there are no 
brackets, the projection of the cornice must be allowed 
for. Lath dots are best for ceiling screeds. They are 
formed at all the angles, and made level all round the 
ceiling. This is done with the aid of a "parallel ceiling 
rule." When all the dots are made, the screeds are fin- 
ished, and the surface flanked in as already described. 
For common work, the wall screeds are seldom 
plumbed; but if there are breaks in the room, the ex- 
ternal angles, which are more noticeable, should always 
be plumbed. For this class of work two men generally 
work together. Working from the floor upwards, one 
man lays a coat of coarse stuff about 7 inches wide, and 
as high as he can conveniently reach up on both sides of 
the internal angles ; his colleague follows on with a float- 
ing rule and rules them straight. Before finishing the 
screed, the rule is applied on the portion done, and grad- 
ually moved up until one end reaches the cornice line, 
to see if there is a sufficient thickness for the upper part 



TERMS AND PROCESSES 109 

of the screed. The space between the first-coating and 
the face of the rule shows the thickness available for the 
floating coat. The desired thickness is obtained by lay- 
ing more stuff on the screed, or working it down, as 
the case may be. As the floating rule cannot be worked 
close up to the angle, a seam of coarse stuff is formed in 
the angle. 

To allow for shrinkage^ and to obtain a flrm and 
square angle, the seams are left until all the floating is 
done, after which they are cut off square and flush with 
the floating. This is done with a laying trowel, w irking 
it on its flat on the firm floating. Any defects in the 
angles are made good when scouring the float- 
ing. After the vertical angle screeds are firm, 
horizontal screeds are laid at the highest conven- 
ient line, and ruled with a floating rule bearing 
on the vertical screeds. The intervening spaces are then 
flanked in by laying with coarse stuff until flush with 
the screeds. The surface is sometimes ruled fair with a 
floating rule, but more often straightened with a darby. 
After the scaffold is erected, the top portions of the ver- 
tical screeds are laid and ruled with a floating rule, 
working it so as to bear on the lower part of the screed 
previously made, which gives a bearing and guide for 
the rule. After allowing for the depth of the cornice 
(if not bracketed), the top horizontal screed is then 
laid and ruled with a floating rule bearing on the ver- 
tical screeds. The intervening spaces are then filled in 
with coarse stuff, and ruled in or darbied as previously 
described. The ceiling screeds are made close to the cor- 
nice bracket, or (if not bracketed) in a line with the 
outer member of the intended cornice. A screed is first 
made at each of the long sides of the ceiling, and when 
firm the end screeds are laid and ruled, using the long 



no CEMENTS AND CONCRETES 

screeds as bearings for the floating rule. If the scaffold 
is in position before the floating is commenced, the 
vertical screeds should be formed in one operation. A 
plasterer on the floor lays the lower part of the screed, 
while his partner on the scaffold lays the upper part, 
after which both work with floating rule together in 
their respective positions. Where practical all screeds 
should be finished in one operation. In the event of a 
screed being too long for an ordinary sized rule to take 
in the whole length and work it in one operation, the 
screed can be made straight by working the rule back- 
wards and forwards from end to end, testing the 
straightness by applying the rule on various parts of the 
screed. The straightness is further proved by lightly 
stretching a chall^-line from one end to the other end 
of the screed. After the screeds are firm, the main 
portion of the ceiling is laid with coarse stuff flush with 
the screeds, and then made fair with a darby. 

When floating large surfaces with a darby, it should 
be worked in all directions — longwise, crosswise, and 
diagonally and finishing with a circular motion. For or- 
dinary work a darby is an excellent tool for straighten- 
ing large surfaces of floating and setting. It also forms 
a pleasing and easy surface on circular work. For base- 
ment and attic rooms a darby properly manipulated will 
form fairly straight screeds as well as the main surfaces. 
When floating large ceiling or wall surfaces for plain 
work, or where it is not necessary that they should be 
perfectly straight, involving time and material, a hol- 
low surface is preferable to a round surface. A hol- 
low surface is not so noticeable, and is less objectionable 
to the eye than a round surface. It will be understood 
that a hollow surface, to be pleasing to the eye if noticed, 
should flow gradually and regular from the screeds to 



TERMS AND PROCESSES 111 

the center of the surface, and not suddenly or in wavy 
parts or patches. 

There is an inferior kind of floating practiced by 
piece-workers, in some districts, for cottage work, and 
even some of the modern jerry-built houses. This is 
executed by floating direct from the walls in one coat. 
The surface is sometimes dry-scoured with a "nail hand 
float, ' ' water and proper scouring being unknown in this 
class of so-called plastering. The ceilings are simply 
laid with coarse stuff, and the ridges and smooth sur- 
face left by the trowel are worked down and roughened 
by a few rubs with a hand float. This porous and cracked 
shell is finished with setting stuff, gauged with just as 
much plaster as will hold the materials together for the 
time being. The minimum of (or possibly less) trowel- 
ling is attempted; a stock brush being found a more 
easy and speedy tool than a trowel for finishing. The 
brush is made to perform the trowelling and brushing 
off in one operation. This shoddy work is unsafe and 
unsanitary, and ought not to be tolerated. 

Scouring Coarse Stuff. — Scouring floated coarse stuff 
is of great importance. It not only consolidates and 
hardens the surface, but also prevents cracks in its own 
body and the subsequent setting coat. For these reasons 
it should be well and sufficiently done. The straightened 
coarse stuff should be allowed to stand to permit of 
shrinkage, evaporation of surface moisture, and a firm 
surface before proceeding with the scouring. Working 
a hand float on a soft surface tends to form ''water 
blubs" and hollow parts. When the surface is firm, 
but not dry, the work is fit to scour. This is done by 
the plasterer having a hand float in one hand, and a 
stock brush in the other, with which he sprinkles water 
on the surface, and vigorously applies the float with a 



112 CEMENTS AND COXCKETES 

rapid circular motion, using a little soft stuff to fill up 
any small holes or inequalities that may have been left 
after the floating rule. Care must be taken that no part 
is missed or less scoured and that the ^hole surface is 
thoroughlv and uniformlv scoured. The floating should 
be scoured twice, or for best work three times, and alLvr- 
ing the work to stand from three to five hours, accord- 
ing to the state of the atmosphere, between the first and 
second scouring, and one day between the second and 
third scouring. The final scouring should be continued 
until there is little or no moisture left on the surface. 
To obtain the same strength and solidity, all other things 
being equal, coarse stuff composed with a weak lime or 
containing inferior or an excess of sand, or having in- 
sufficient hair, or sparsely tempered and used in an 
over-soft condition, recjuires a greater amount of scour- 
ing than coarse stuff which is composed with a strong 
lime, or containing good sand and in due proportion, or 
with an ample quantity of hair, or well tempered, and 
used in a mioderately stiff yet plastic condition. Even 
vrith extra scouring the ultimate strength of inferior 
coarse stuff is remote and doubtful. This simple mat- 
ter is a witness to the fact that inferior or insufficient 
materials reciuire more labor than good and sufficient 
materials and that the results are somewhat vague and 
often unsatisfactory. 

Keying. — All plastic materials have great adhesive 
powers, especially to each other. Yet when laying a thin 
bodv of fine material on a coai-se material which has a 
more or less smooth, dry and absorptive surface, such as 
lajing setting stuff on fioated coarse stuff, the adhesion 
is partly nullified. Portland cement or hydraulic limes, 
which set nearly as soon as laid, rec[uire no scouring, and 
being left from the floating rule with an open grained or 



TERMS AND PROCESSES 113 

rough surface, a natural key is obtained for the final 
coat; but coarse stuff, which only sets or becomes hard 
by evaporation of its moisture, must be scoured to con- 
solidate the yielding and soft bod}^ Scouring leaves a 
close-grained and somewhat smooth surface, offering lit- 
tle or no key to the setting coat. The floated coat being 
often dry before the setting coat is applied, the suction 
varies greatly; sometimes it is regular, at other times it 
occurs in patches. Sometimes the suction is so excess- 
ive that the setting stuff dries up and peels as soon as 
laid, and in other instances the reverse occurs, there 
being no suction at all. In the latter case the setting 
stuff runs downwards in the form of globules or in rivu- 
lets. These defects may to a certain extent be corrected 
by laying the setting stuff while the floating is still 
green, or by saturating the surface if the floating is dry. 
Yet to obtain permanent cohesion in the two coats it is 
necessary to key or roughen the surface. This is best 
done by brushing the surface as soon as scoured with a 
stiff whalebone broom cr with a wire brush. A common 
plan is to dry scour with a ''nail float" — i. e., a hand 
float with the point of a nail projecting about % inch 
beyond the sole of the float. When this method is em- 
ployed the float should be worked in a cLse circular 
motion so as to leave a series of close and irregular in- 
dents. The usual and careless way of working the float 
in a wide circular motion leaves the indents too wide 
apart to give a sound and uniform key: indeed, this 
method is of little service. A n^w tool for keying coarse 
stuff has been recently introduced, which is called a 
''devil" and is similar to the nail float, with the excep- 
tion that there are four nail points projecting on the 
sole, one of which is placed about II/2 inches from each 
angle. The process of keying the coarse stuff with this 



114 CEMEXTS AXD CONCRETES 

is termed ' ' devilling. ' ' The work is more speedily and 
better done with the "devil" than with the nail float. 

After the floating is finished the next part of interior 
plaster work is the running of the cornice, and then fm.- 
ishing the ceiling and walls: bnt in order to continue 
the methods of setting, the running of the cornice, etc., 
are described in subsequent pages, and the setting and 
other parts of wall work are first described as follows: 

Setting. — Setting is the laying and fiuishing the final 
coat on floating, termed "finishing," and "hard finish" 
or "putty coat." In the best work great skill and care 
is required to make the surfaces perfectly true and uni- 
form in color, smoothness and hardness. The material 
for three-coat work is generally known as "setting 
stufi:. " The mode of makins has alreadv been de- 
scribed. Setting stufi: should not be applied until the 
floating is quite flrm and nearly dry. to allow for any 
contraction that may take place in the floating. If the 
floating should become quite dry during the time re- 
ciuired for cornice and ceiling work, or where subjected 
to strong winds or a warm atmosphere, it should be well 
wetted a day or two before the setting coat is com- 
menced. This prevents the too rapid absorption of mois- 
ture from the setting coat and gives a closer union of 
the floating and setting coats. Before wetting copi- 
ously, a small portion of the floating should be tested 
with a wet brush to ascertain the degree of suction. In 
some floating there is no suction, or at least there is 
none until the surface has been dampened and the glaze 
and sometimes grease has been washed ofi\ Glaze is 
caused bv slisiitlv hvdraulic lime, also bv insufficient 
scouring. Glaze is more noticeable on first-coating 
which has been left smooth by the laying trowel. Grease 
occurs throuofh friction, also dirt where the float is left 



TERMS AND PROCESSES 115 

long exposed. These matters of excessive and non- 
suction, dry, glazed or greasy surface, either singly or 
in combination, also smooth or unkeyed floating, are the 
cause of cracked or scaly setting, which one sees more or 
less in a plaster career. It is therefore absolutely neces- 
sary, to insure perfect cohesion of the two coats, that 
the floated surface should be uniformly keyed, clean and 
damp before the setting coat is layed. Setting consists 
of laying the stuff, scouring, trowelling and brushing the 
surface. 

Laying Setting Stuff. i — The setting stuff is laid in two 
coats, the second following immediately upon the first. 
The laying is best done with a skimming float, which 
leaves the face of the first coat rougher to receive the 
second than if done by a laying trowel, which leaves it 
smooth. The second coat should also be laid with a 
skimming float, which leaves a more open grain for the 
purpose of scouring. When laying setting stuff some 
men take a trowelful or skimming-fioatful off the hawk 
and stoop to spread the stuff from bottom to top with 
an upward motion, laying the joint with a return down- 
ward motion; but a smart man can take a trowelful or 
floatful of stuff and spread it with a downward motion 
from top to bottom and lay the joint with the return mo- 
tion, this saving one stoop in each spread or floatful. 
This is similar to laying setting stuff on a ceiling. A 
man who has a thorough command of the trowel hand 
always lays the stuff in a long even spread outward, 
and lays the joint with the inward return motion. After 
one side of a bay or wall is laid the surface is then 
scoured, trowelled and brushed. 

Scouring Setting Stuff. — The importance of good and 
sufficient scouring of setting stuff with water cannot be 
too strongly insisted upon. The scouring and the water 



116 CEMENTS AND CONCRETES 

combined consolidate, harden and render the surface of 
a uniform texture and evenness. The work must be well 
and thoroughly scoured, twice with water and an ordi- 
nary hand float and finally with a cress-grained float. 
The hand fl_at is worked with a short and rapid circular 
motion and sprinkling water uniformly with a stock 
brush until the surface is uniform in moisture and tex- 
ture. After a rest to allow the stuff to shrink the scouring 
is repeated, and then it is ready for the final scouring. 
This is best done with a cross-grained hand float, which, 
having sharp sc{uare edges, cuts ofi^ all ridges and leaves 
the setting with a uniform and even surface that cannot 
be so quickh^ or as well done with an ordinary hand float. 
Water is more sparingly used for the final scouring, 
using only as much as will moisten the surface and allow 
the float to work freely. The scouring is continued until 
a dense, even and close-grained surface is obtained for 
the trowelling. 

Troivelling and Brusking Setting Stuff. — Trowelling 
setting stuff is best done by the use of a half worn 
trowel (commonly called a "polisher"), the edges of 
which should be perfectly straight and parallel. Some 
men use an old and worn trowel with the point narrower 
than the heel. This shaped trowel should never be used 
for high class work, since, not being parallel, the press- 
ure when trowelling is not equal, and the heel or widest 
part is apt to score the surface of the setting. The 
trowel and water should be perfectly clean to prevent 
any discoloration. The trowelling should be done by 
one man following up the other, who is finishing the final 
scouring. This is done by the plasterer ha^dng a polish- 
ing trowel in one hand and a stock brush in the other, 
with which he sprinkles water on the surface and works 
the trowel in long and vigorous strokes, first downwards 



TERMS AND PROCESSES 117 

and upwards, and then crossways or diagonally. This is 
repeated, using the water more sparingly and finishing 
or "trowelling off" with an up-and-down motion and 
leaving the surface free from "fat" or "glut." The 
work is then brushed with a wet stock brush, first up and 
down, then crossways, afterwards up and down a sec- 
ond time. The brush is then semi-dried by violent shak- 
ing, or rubbing on a clean board, the work again being 
brushed as before and finished perpendicular. 

General Remarks on Setting, — When the work is re- 
quired for painting the setting stuff is laid on the form 
of screeds, and when firm the intervening spaces are 
laid flush with the screeds and the whole surface ruled 
fair with a floating rule. Should there be any hollow 
or soft places (the latter being liable to shrink), they are 
filled in with more setting stuff' and ruled over again. 
This is repeated until the whole surface is true and uni- 
form in thickness and firmness. The whole surface can 
be scoured, trowelled and brushed in one operation. 
This method has the advantage of saving joints at the 
connections between the height a man can lay and finish 
the setting stuff. 

Joints, unless carefully done, are an eyesore, as they 
are liable to be more or less discolored and uneven on 
the surface. The best method for making joints and 
setting stuff, where it is inconvenient to lay and finish 
the whole surface in one operation, is to leave the edge 
of the joint untrowelled, leaving a scoured margin so 
that the adjoining portion can be laid and scoured with- 
out spoiling the trowelling of the first portion. For in- 
stance, when setting the walls of a room one scaffold 
high the top parts are laid down to the level of the 
scaffold, or as far as convenient, and the surface scoured 
and trowelled. The latter must not extend to the end 



118 CEMENTS AND CONCRETES 

of the scoured part, so as to leave an untrowelled margin 
about 4 or 5 inches wide until the scaffold is struck. 
After the scaffold is removed the lower portions of the 
walls are laid flush with the untrowelled margin, and 
then the surface is scoured as before, always going well 
over the joint. The surface is then finally scoured with 
a cross-grained float, taking care to moisten and rescour 
the untrowelled margin to render the whole of the 
scoured surface equal in texture and moisture for trowel- 
ling. The surface is then trowelled and brushed as al- 
ready described, taking care to go over the trowelled and 
brushed joint. By this method no joints are visible, and 
an even surface is obtained. When the suction is slow 
or irregular, causing the setting stuff to run or be soft 
in places, float the surface with a darby until sufficiently 
fair and firm to be scoured. A darb}' is very useful for 
forming a fair surface on setting stuff before scouring 
and trowelling. It forms the next best surface to a 
ruled surface. A darbied surface is better and truer 
than a laid surface. 

No more setting stuff -"hould be laid than can be con- 
veniently finished in one operation or day. Where prac- 
tical, one side of a wall should be finished in one piece, 
and sufficient men should be employed thereon. If the 
room is not too high, one man or set of men may do the 
upper part, while another man or set of men does the 
lower part. The joints are then made while the setting 
stuff is green. In high rooms, several sets of men work 
together on different scaffolds, each about 6 ft. 2 in. 
apart. All angles should be ruled in with a long float- 
ing rule. External angles are sometimes formed by 
nailing a running rule or a straight edged plumb on one 
side of the wall, to act as a guide, but external angles are 
generally finished with a run cement bead or an arris. 



TERMS AND PROCESSES 119 

An average thickness of % inch of setting coat when 
finished gives the best result. It should not exceed 3-16 
inch, or be less than 1-16 inch in thickness. If too thick, 
it is liable to crack and flake; if too thin, it is liable to 
peel. Where extra strength, and cohesion between the 
floating and setting coats is desirable, the first coat of the 
setting has a little white hair mixed with it. White hair 
does not show through the last coat. 

Common Setting. — Common setting for wall and ceil- 
ings is generally used for second-class work. It is done 
by laying one coat of setting stuff with a skimming float, 
and scouring and trowelling once and brushing twice. 
Where the floating cracks by contraction, or by using in- 
sufficient hair in the coarse stuff, or by want of scouring, 
or where the work is green, the cracks are knocked in 
with a hammer. The indents are then filled up with 
gauged setting stuff, and the whole surface laid with a 
coat of this material, on which a coat of neat setting stuff 
is laid, scoured, trowelled, and brushed in the usual 
way. 

Skimming. — Skimming is an inferior class of setting, 
and is only used for the most common work. It is done 
by laying a coat of fast-setting stuff with a laying trowel. 
The stuff is skimmed over the floating as thin as possible, 
using only as much stuff as will whiten and smooth the 
floating surface. It is trowelled once, and brushed as 
soon as laid. 

Colored Setting. — A beautiful color and brilliant finish 
for walls is obtained by mixing an equal quantity of 
sifted marble dust with setting stuff and using this 
"marble setting stuff" as a final coat. Ordinary setting 
stuff is greatly improved by substituting a part of mar- 
ble, or alabaster, or gypsum dust, equal in bulk to half 
the sand generally used. The marble dust should be as 



120 CEMENTS AND CONCRETES 

coarse as the sand. Crushed spar is sometimes used in 
setting stuff to obtain a sparkling surface. Barytes, sco- 
ria, and slag are sometimes used as a substitute for sand, 
for coloring and hardening purposes. Brick dust is also 
used for coloring, and weather and heat resisting pur- 
poses. Ground glass as used by Indian plasterers gives 
a sparkling surface. Setting stuff may also be colored 
with the same materials as described for colored stucco. 
Where marble dust or any of the above materials are 
used, they should not be added until the setting stuff is 
required for immediate use. They should not be used 
until perfect amalgamation has ensued. 

Gauged Setting. — Gauged setting is used where the 
floating is soft, or where the work is required for imme- 
diate use, and also for finishing gauged floating. This 
is performed by one man laying the gauged stuff with 
a skimming float, while his partner follows up with a 
darby to lay the surface fair. Another batch of setting 
stuff is then gauged, and one man lays a thin coat with 
a trowel, and the other man follows immediately and 
trowels the work before it is set. The surface is finished 
by brushing with a semi-wet brush. Gauged setting 
should never be scoured unless the size water is used in 
the gauge to delay the setting, as it will kill the plaster 
and render the stuff useless. Even if size water is used, 
the scouring must be slightly and quickly done. If a 
•gauged surface is desirable, a fair and hard surface is 
obtained by simply darbying and trowelling as soon as 
laid. 

Gauged Putty Set.\ — Ceilings are sometimes set with 
gauged putty. This is best done by first laying a 
"scratch coat" of gauged putty with a skimming float, 
and then passing a hand float over the surface (before 
the stuff is set) to lay down any ridges, and make the 



TERMS AND PROCESSES 121 

surface more even to receive the second coat. This is 
laid with a laying trowel, and then trowelled before the 
stuff is set. The surface is then finished with a semi-wet 
brush. Trowelling after the stuff is set, or even has 
begun to set, kills the stuff, and causes it to peel. A 
little washed sand added to the putty makes a stronger 
surface, and not so apt to peel. 

Putty Set. — In some districts common ceilings are fin- 
ished with a thin coat of neat lime putty ; but unless the 
putty is made from grey limestone, or is of a hydraulic 
nature, the work is more or less weak, and in most cases 
practically useless. 

Internal Angles. — The setting coat of internal angles 
on room walls should be ruled fair and then cleaned out 
with a feather-edged rule. Before scouring the setting 
stuff, the angles should be squared and made straight 
with an angle float. The angle float is a tool now unfor- 
tunately seldom used, but it is the best tool for making 
a true angle. In the absence of an angle ficat, the angle 
should be made fair and square with a cross-grained 
float, and finished with a margin trowel or the heel of a 
laying trowel. The common way, used in some districts, 
of finishing an angle with a gauging or pointed trowel, 
should not be encouraged, as it is impossible to make a 
true angle with a tool of this shape. 

External Angles. — The external angles of room walls 
and windows are generally finished with a bead, but in 
some instances with a plain arris, splay, or small mould- 
ing. They are formed with Parian or other white 
cement, and usually run after the floating is done. The 
floating should be cut square on each side, and down to 
the brick or lath work. After dusting and wetting the 
foundation, a running rule is fixed on one side, and then 
the bead or arris is run. The run edges form bearings 



122 CEMENTS AND CONCRETES 

for the setting coat. A run arris is more speedily done 
and truer than a ruled and trowelled arris. In some 
districts wooden beads are used for external angles. The 
floating is cut down at each side of the bead, to allow the 
quirks to be formed Avhen the setting coat is laid. When 
the setting coat is trowelled, the quirks are formed by 
applying a large-headed nail on the bead, and drawing 
it up and down to cut the stuff out. They are then fin- 
ished by working a laying trowel up and down until 
smooth and true, and afterwards wet-brushed. The 
bead quirks are sometimes cut out by aid of a wooden 
template, also by laying a straight edge on the work as 
a guide for cutting the stuff out. They are then finished 
with a trowel and brush, as already described. 

Skirtings. — Skirtings or base, are sometimes formed 
in wood, but are often formed in cement. Cement skirt- 
ings are far more sanitary than wood skirtings, as the 
former connects the wall and the floor in one solid fire- 
resisting and vermin-proof body, whereas wood skirtings, 
owing to their nature and construction, afford a ready 
harbor for vermin, and offer but little or no resistance 
to damp and fire — indeed, their hollow formation pre- 
sents a vent in the case of fire. Parian or other white 
cement is generally used where a fine finish is desirable, 
and Portland cement where the work is exposed to wet 
and hard wear. Skirtings are generally run by first 
roughing out the plinth by aid of a gauge rule bearing 
on the floating, and then forming a running screed, and 
fixing a running rule on the plinth. The skirting mould- 
ing is then run in the usual way, after which the running 
rules are taken off, and the plinth set. The mould plate 
should be cut to form about 1 inch of the top part of the 
plinth, to form the arris, and a bearing when setting the 
plinth. The annexed illustration (No. 4) shows the 



TEEMS AND PROCESSES 



123 



method of forming the core and plinth, and running 
the moulding. Pig. 1 shows the gauge rule (G) in posi- 
tion to form the core ( C ) . The gauge rule is from 3 
feet to 4 feet in length. The plinth is formed by first 
roughing out with gauged stuff, and then drawing the 
gauge rule along the floating to form the core, and a 
fair surface for the running screed. Pig. 2 shows a sec- 
tion to form the core (C). The gauge rule is from 3 
(R) fixed on the plinth or core (C). 




rSKIRTING FORMATION. 
NO. 4. 



Two-Coat Worh. — This is a cheap method of plaster- 
ing, and only used for common work, such as the walls 
of factories, warehouses, &c. It is performed by laying 
one coat of coarse stuff and then forming the surface 
fair with a darby, after which it is scoured once. It is 
then finished by laying a thin coat of setting stuff over 
the surface, and then trowelling once and brushing twice 
wet and once semi-wet. 

One-and-a-Half-Coat Worh. — This is sometimes termed 
* * coat-and-half work." It is a species of two-coat work 
^n fact^ it is so termed in some districts. It is done by 



124 CEMENTS AND CONCRETES 

first laying a coat of coarse stuff fair, and then scratch- 
ing the surface with a coarse broom, after which a thin 
coat of extra fat coarse stuff is laid, straightened with a 
darby, and then trowelled and brushed. The second coat 
must be laid while the first is green. This permits the 
two coats to amalgamate better, and the surface to be 
more easily worked and finished. 

Stucco. — Stucco is an Italian term usually applied in 
Italy to a superior species of external plastering. Ac- 
cording to Vasari, Primaticcio ' ' did the first stucchi ever 
executed in France, and also the first frescos." In the 
United States stucco is a somewhat indefinite term, used 
loosely for various plastic mixtures in whose composi- 
tion lime, plaster, or cements enter. Hydraulic lime 
was formerly used for external stucco. Roman cement 
was extensively used for stucco fronts during the first 
half of the present century. Selenitic lime has some- 
times been used for a similar purpose. These materials 
are now entirely superseded by Portland cement. The 
adoption in England of stucco externally to give brick 
houses the appearance of stone is due to Robert Adam. 
Its plastic nature enables it to adapt itself to most archi- 
tectural purposes with very considerable decorative ef- 
fects. The more general use of stone and the improve- 
ments in terra cotta have so greatly decreased the use of 
stucco for fronts, that stucco has become a synonym for 
a sham, and its real usefulness for certain works and 
places has been greatly overlooked. When properly pre- 
pared and manipulated it makes excellent work, and in 
the near future a large use may be predicted for its use. 

Old Stucco. — It has already been shown that stucco 
was largely employed by the ancients for plain and dec- 
orative purposes. The temple of Apollo at Delos, and 
even the first Parthenon under the ^Eons of Pallas her- 



. TERMS AND PROCESSES 125 

self, were plastered with stucco. Vitruvius in his sev- 
enth book mentions stucco under the name of opus al- 
larium, sometimes written album opus. Tectorium opus 
(from tector, a plasterer) was a name given by the Ro- 
mans to a mortar used for plastering. According to 
Yitruvius, Palladius, and Pliny, there seems to have been 
a difference between tectorium opus and that called al- 
barium or album opus. Vitruvius says tectorium was 
composed of three coats of lime and sand, and three of 
lime and marble. According to Winckelman, the united 
thickness of these coats was not more than one inch. 
The first coat was of common, but old, lime and sand, 
and when it was nearly dry a second coat of lime was 
laid, and on this drying a third coat of fine lime was laid 
and made fair. The work w^as then laid with another 
two coats of lime and marble, and finished with a coat 
of fine marble powder. The marble mortar was fre- 
quently beaten to render it tough and yet plastic, and 
it was judged fit for use when it would no longer stick 
to the trowel. When the lime mortar was dry, the mar- 
ble mortar was laid, each successive coat of marble mor- 
tar being laid before the preceding one was quite dry. 
The first coat of marble mortar was composed of coarse 
ground marble and old lime, the second of fine ground 
marble and lime, the finishing coat being neat marble 
ground to a fine powder, and laid before the second coat 
was dry, and worked with a wood float until the surface 
was consolidated and straight. When dry it was pol- 
ished with lime and chalk or with marble until like mar- 
ble itself. Old stucco has been found so hard and highly 
polished that it has been used for looking-glasses and 
tables. In time it became hard and not liable to crack, 
and formed an excellent ground for the painting with 
which the Greeks and Romans decorated the walls of 



126 CEMENTS AND CONCRETES 

their houses. According to Vitruvius, this painted plas- 
ter could be detached without fear of injury, and de- 
tached slabs were carried to Italy and inserted in the 
walls of Roman houses. To prevent the cracking of the 
work done on wood, it was strengthened by two layers 
of reeds, one layer crossing the other at right angles. 
To insure dryness, and allow the plaster to attain its 
proper hardness, the walls were perforated at suitable 
places. The tectorium was then decorated with brilliant 
colors, which were applied on the last coat while it was 
fresh; and to heighten the brilliancy and endurance of 
the colors the surface was rubbed over with wax and 
pure oil. When marble was used with lime in place of 
sand it was termed martmoratum. The alburium or 
albuiQ opus was what we term plaster or stucco. The 
Greeks named tectorium and alburium, koniama and 
kalachrisis. 

Slabs of tectorium from the walls of Pompeii and Her- 
culaneum are now in the Museum of Portici, and speci- 
mens are also in the South Kensington Museum. In the 
Museum of Practical Geology, London, there are several 
pieces of old plaster, taken from the ruins of Pompeii, 
some of which show that the decorative colors were not 
applied a la fresco, but subsequent to the polishing. 
Stucco and plaster are really two very different things. 
Stucco has for its base carbonate of lime, generally burnt 
limestone or chalk, with which putty lime and coarse 
stuff is mixed with sand, &c., and used for plastering 
walls and ceilings. Plaster has for its base sulphate of 
lime, being made from gypsum, and is used for cast 
work and gauging with lime putty, &c. The best kinds 
of stucco will resist the action of weather, and can be 
washed. Plaster, unless specially prepared or indurated, 
perishes by exposure, at least in our climate, and cannot 



TERMS AND PROCESSES 127 

be washed. Stucco is a superior kind of mortar, and it 
raay be used for plastering or for modelling. The ad- 
mixture of various materials with lime and with plaster 
to form stucco is referred to by many ancient writers. 
Pliny mentions fig juice as being mixed with stucco. 
The Egyptians mixed mud from the Nile with plaster 
for some of their work. Elm bark and hot barley water 
was mixed with the stucco for Justinian 's Church of the 
Baptist, Constantinople. We find bullocks' blood em- 
ployed for this purpose as well in mortar for Rochester 
Cathedral in the latter part of the ninth century. Bishop 
Gundulph (1077-1108) is stated to have mixed blood 
with lime to make it hard. Hot wax mixed with lime 
was used at Rockingham Castle in 1280. White of eggs 
and strong wort of salt were mixed with lime used for 
Queen Eleanor's Cross at Charing Cross in 1300. Pitch 
and wax were mixed with the lime used for Edward 
IL's works at Westminster in 1324. Mediaeval build- 
ers habitually used beer, eggs, milk, sugar, gluten, &c., 
for mixing with mortar for cathedrals. Frequent en- 
tries found in the archives prove this. One reads, ''For 
beer to mix with the mortar. ' ' Bess of Hardwicke 's ma- 
sons used beer in their mortar, having to melt it in the 
cold winter of her death. Old plaster is found to have 
rye straw mixed with it for binding, and was very strong. 
A brown substance somewhat like plaster, but full of 
fibre, was in use in the sixteenth century. The accounts 
for the repairs of the steeple of Newark Church in 1571 
contain an entry, "6 strike of malt to make mortar to 
blend with ye lyme and temper the same, and 350 eggs 
to mix with it." During the building of the Duke of 
Devonshire's house at Chiswick, the exterior of which 
was plastered with stucco, the surrounding district was 
impoverished for eggs and butter-milk to mix with the 



128 CEMENTS AND CONCRETES 

stucco. Peter le Neve's mention of rye dough stands 
not alone, as Sir Christopher Wren's "Parentalia" 
(1750) records the use of "marble meal" as the old and 
still the modern way of stucco work in Italy. "Marble 
meal" simply meant marble dust ground as fine as meal. 
This dust was used fo^ fine work. Sugar and the gluten 
of rice are used in Ceylon and India. The Chinese use 
a rich unctuous earth in combination with lime. In some 
parts of France urine was used with plaster in the six- 
teenth century. Nearly all these admixtures are to re- 
tard the setting, to allow more time fcr the manipulation 
of the stuccos. Some are to accelerate the setting, and 
some are to increase their ultimate hardness. 

Many of the ancient buildings in various parts of the 
universe, which were built of mud, clay, or sun-dried 
bricks, had their surfaces decorated with hand-wrought 
stucco. During explorations in Peru, South America, 
Dr. Le Plongeon found some interesting specimens of 
ancient plaster work in a number of the ruins of the 
early Peruvian houses and cities, which date back to re- 
mote antiquity. At Chenni Concha he found the frag- 
ments of some ancient ornamental stucco on the adobe 
(or clay-built) walls, covered with bas-relief decorative 
designs,, while the material is after many centuries still 
in good preservation. The design and the execution are 
of considerable merit, and it seems wonderful that a 
people ordinarily held to be but little better than savages 
could have conceived ornamentations so aesthetic, and 
have executed them with such high technical ability. 

Cav. M. Geggenheim, who has had much stucco work 
done in the Palazzo Papadopcli and elsewhere, gives the 
following formula for the stucco duro which is still used 
in Venice : It is old stone lime, slaked for three years 
at least, mixed with Carrara marble dust, ground as fine 



TERMS AND PROCESSES 129 

as flour, into the consistency of paste. This of course 
is for the finishing coat, the rough modelling being ex- 
ecuted with a coarser material. 

There are four kinds of so-called stuccos which are 
used in this country. They are known as common, rough, 
bastard, and trowelled. The methods of working these 
species of plastering are embodied in the description of 
three-coat work — in fact the only difference between 
these stuccos and three-coat work lies in the setting coat, 
the first-coating and floating being the same for all. 
Some of the above terms are now only used by work- 
men, and the use of stuccos is to a great extent super- 
seded by Portland cement for exterior work, and Parian 
and other white cements for interior work. The follow- 
ing is a summary of the materials and methods used for 
the various stuccos. 

Common Stucco. — Common stucco was principally 
used for exterior work. It is composed of 3 parts of 
coarse sharp sand to 1 of hydraulic or grey lime, to which 
a small portion of hair is added. It is laid in a similar 
way to ordinary rendering in one coat, and the surface 
finished with a hand float. 

Rough Stucco. — This is generally used for plastering 
churches, corridors, and entrance halls to imitate stone. 
The work is floated with ordinary coarse stufl^, and then 
set with stuff composed of 3 parts of washed sharp sand 
and 2 of grey lime putty, not chalk. This is laid with 
a trowel, and then ruled in with a straight edge until 
the surface is full and fair. After this it is scoured 
with an ordinary hand float, and finished with a "felt 
float," not to raise the grit, but to keep it down. The 
felt float is an ordinary hand float with an unplaned 
sole, on which a felt scle, about 1^4 i^ch thick, is fixed 
with gauged plaster. This tool before using generally 



130 CEMENTS AND CONCRETES 

requires to be rubbed on a straight stone to obtain a uni- 
form face. Great care must be exercised when laying 
and finishing the surface, so that no joints are shown, 
or else they will never dry out. When wanted to repre- 
sent ashlar masonry, the surface is set out with lines to 
the size of the required stones, and then the lines are 
indented to form the joints with a jointer or the ring 
end of a key. The grain of the stone can be better imi- 
tated by patting the surface with the hand float as a 
finish. The staining of stucco to represent the color of 
stone is done by diluting sulphuric acid (oil of vitriol) 
with water, and mixing with it the liquid ochres and 
other colors to the required tints. The setting stuff may 
also be mixed with the ochres before using. A small por- 
tion of the colored stuff should be dried to ascertain the 
tints before laying the whole surface. 

Bastard Stucco is somewhat better in quality than or- 
dinary setting. The final coat is composed of 2% parts 
of washed sharp sand and 2 parts of chalk lime putty. 
It is laid in two coats with a skimming float, scoured up 
once and then trowelled off and brushed. 

Trowelled Stucco is generally used for work that has 
to be subsequently painted. The stuff for the finishing 
coat is composed of from 2% to 3 parts of washed sharp 
sand to 2 parts of chalk lime putty. The sand is not so 
fine as that used for ordinary setting, being washed 
through a sieve having about 12 mesh to the inch. The 
stuff is laid on, and then traversed with a floating rule 
in all directions, up and down, across and diagonally. 
The surface is then scoured up without water, and after 
a rest to admit of shrinkage, the surface is scoured up 
three times with water ; the trowel to immediatelv follow 
the third scouring up. This trowelling is continued 
until the work becomes so hard that no impression can 



TERMS AND PROCESSES 131 

be made on the surface; it is then brushed off with a 
soft damp brush (not wet), first horizontally, then diag- 
onally, and finally perpendicularly, leaving a brilliant 
face. When dry, the gloss goes off, and leaves a fine 
surface for paint. 

Colored Stucco. — The Italians execute lime stuccos in 
colors, mixing in the lime various oxides — i. e., blacks 
are obtained by using forge ashes containing particles of 
iron; pearl greys are made by mixing ashes with the 
marble ; greens are obtained by using green enamel, with 
a large proportion of marble powder, worked up with 
lime-water; browns by mixing ashes with the lime and 
marble in proportions varying with the tints desired; 
reds by using litharge, or the red oxide of lead; blues 
by mixing 2 parts of marble powder and 1 of lime, and 
% of oxide, or carbonate of copper; Stucco may also 
be colored with the same materials as described for 
colored setting, also for sgraffito and concrete. 

Method of Working Keen's, Parian, and Martin's 
Cements. — When describing the technique or practical 
manipulation of Parian and the other white cements 
which have been invented in the nineteenth century, it 
is only natural that one should feel animated by a pecu- 
liar pleasure, because in these cements, our industry, 
aided by modern science, has, as far as is known, 
equalled, if not excelled, anything of the kind produced 
by the ancients, tested by any experiment, whether for 
strength, solidity, or durability. With these a great sav- 
ing in time can be effected, as work can be begun and 
finished in one operation, without waiting for the differ- 
ent coats to dry, as in ordinary lime plastering. For 
sanitary purposes they are unequalled. This, combined 
with their chemical properties, which enables them to be 
painted, papered, or distempered as soon as finished. 



132 CEMENTS AND CONCRETES 

renders them the most valuable of all plastering materials 
in this go-ahead age. They are free-working, sanitary, 
durable, and practically fireproof. They are the very 
best materials for plastering walls, dadoes, or in similar 
exposed positions. For skirtings they are invaluable, 
as they offer an effectual resistance to fire, vermin, and 
dust. When properly manipulated, they can be worked 
to a porcelain-like surface. They are nearly perfection, 
and constitute perfect plasters for most interior work. 
Their onl}^ drawback is that they will not resist the ef- 
fects of moisture. It is therefore imperative that damp 
walls should be floated mth Portland cement, where 
a white cement finish is desirable. Bv the aid of the 
hard and sanitary white cements plastering has become 
a tangible reality, instead of a comparative makeshift, 
which it has hitherto been. The object aimed at in the 
invention of white cements for internal use is to pro- 
duce a material of which plaster is the base, which shall 
set sufficiently slow to be easity manipulated, become 
dense, hard, non-porous, and may be painted as soon as 
finished. Before the introduction of these cements, all 
making good, as it is technically called (i. e., patching 
holes in old plaster work), used to be done with neat 
plaster, plaster and sand, or lime gauged with plaster. 
Keen's was first introduced, then Parian, and lastly 
Martin 's. Parian being most in demand, claims priority 
in description. Parian and other white cements are uni- 
formly reliable in quality, but through the rapacity of 
some contractors the cements are often adulterated with 
plaster to lower the cost, and hasten their setting. This 
adulteration causes the cement to swell, and in many in- 
stances to peel or fall off. Even if it does adhere, it 
never attains its due hardness, and thus is no better than 
ordinary plaster. Unfortunately adulteration brings 



TERMS AND PROCESSES 133 

discredit on the cement and the trade. The only remedy 
is proper supervision by a plasterer who possesses a thor- 
ough knowledge of plastic materials and the methods of 
using them. If plasterers were awarded certificates of 
competency, adulteration would be prevented, and good 
work ensured. Honest employers would find this bene- 
ficial, for scampers can only thrive where there is a lack 
of knowledge of the technique peculiar to plastering, 
and which only plasterers of experience really possess. 

In using Parian cement on lath-work, exceptional care 
must be observed that all the lath nails be galvanized, 
or painted over, or coated with shellac, to prevent rust. 
For this same reason all nails used for plumbing and 
levelling purposes must be extracted after the screeds 
are set. For first-coating and floating ceilings with this, 
material, the proportions for best work are 1 part of 
cement to 2 of clean sharp sand, adding about the same 
quantity of hair as for lime plaster. Walls are generally 
floated with Portland cement in the proportion of 1 part 
of cement to 3 of sand, and finished with neat Parian. 
This system is adopted as a matter of economy, as Port- 
land cement is cheaper than Parian; and where time is 
no particular object, makes equally as good work. For 
walls intended to be painted or polished immediately, it 
is necessary to mix the materials in the same proportion 
as for ceilings, with the difference that more sand may 
be used — say 2 parts of cement to 5 of sand. The rea- 
son for this is, that when floated with Portland, and 
finished with Parian an efflorescence invariably appears 
on the finished surface, and until it has time to dry out, 
it is inimical to successful painting or polishing. Gaug- 
ing is an important point; it must be carefully and 
quickly done to insure success and obtain the full 
strength of the cement. For first-coating or floating 



134 CEMENTS AND CONCRETES 

ceilings, empty a sackful, or half a sack according to 
requirements, in a clean banker; then add the sand in 
the proportions already given, and thoroughly mix the 
cement and sand while yet dry; then form a ring, and 
pour in the water, taking care not to pour in too much, 
as it must be gauged, and used as stiff as practicable. 
There will be no difficulty in thus using it, as it will take 
some hours to set, according to the season of the year 
(quicker in summer than in winter). "When the water 
is in, add the hair (which must previously be well beaten 
and soaked), and gauge the whole mass together. Then 
begin the first coating, scratch it in the usual manner, 
and so on, until the whole ceiling is first-coated. It 
should stand for twenty hours before starting to float. 
Hair is generally omitted for common work, or where 
the laths are close. 

Parian cement ceilings should be dead level, and have 
a uniform and straight surface; therefore the screeds 
should be levelled, made narrow, and the sides cut square, 
and when firm the whole ceiling should be ruled in with 
a floating rule, sufficiently long to reach from screed to 
screed. The floating stuff is gauged moderately stiff, 
and laid diagonally across the line of laths, so as not to 
spring the lath-work, or disturb the key of the first-coat- 
ing. After the ceiling has been laid, the floating rule is 
applied, a man holding each end (and one at the center 
if extra long). It is then drawn gently and steadily 
along, filling up hollow places, until the whole surface 
is straight and true. When the surface is firm, it is 
brushed with a coarse broom to form a key for the finish- 
ing coat. If there is a Parian cement cornice to be run, 
the usual mode for plaster and putty is adopted for the 
running rules. The screeds should be made sufficiently 
smooth to run on, without forming an extra thickness or 



TERMS AND PROCESSES 135 

traversing screed. The cornice is roughed out with the 
same kind of material as used for the floating, employ- 
ing a muffled running mould for running the rough stuff. 
It may not be practical to rough out all the cornice at 
once, as this stuff does not set quick, therefore it may be 
necessary to leave it for a time until the stuff stiffens. 
No definite directions can be laid down in this matter, as 
the suction is greater in some seasons and rooms than in 
others. A little extra hair, also extra stiff gauging, is of 
service to make the stuff cling together, thus allowing 
the work to be roughed out sooner. The running moulds 
must be made of strong zinc or copper (no iron to be 
used on any account). Where the work is in cornices, 
skirtings, achitraves, &c., the mould should be muf- 
fled with a zinc or copper plate. If there is only a small 
quantity to be run, a plaster muffle may suffice. After 
the cornice is roughed out, it is finished with neat Parian, 
and then the mitres formed in the usual way. 

In preparing to finish a large space (ceilings or walls) 
it is absolutely necessary that no more should be laid 
than can be finished the same day, therefore as many 
men should be put on the job as will accomplish that 
object, as no sign of a joint should be shown on the sur- 
face. In the case of large or high walls, the scaffold 
should be so arranged that the men can work the whole 
wall from the cornice down to the skirting in one opi ra- 
tion. If a wooden skirting has to be subsequently fixed, 
one end of the rule bears on the fixing grounds ; but if a 
Parian skirting or base is specified, it is generally run 
before the walls are finished, and allowed to get thor- 
oughly hard, so as to bear the end of the rule used for 
the finishing coat. The lower end of the rule is cut to 
fit the upper member of the skirting. Another way is 
to nail a board onto the end of the rule, so that it bears 



136 CEMENTS AND CONCRETES 

well on the plain plinth and clears the members of the 
skirting. The cornice screed must be keyed with a drag 
before the finishing coat is laid. For large cornices it 
is often desirable to traverse the running screeds. In 
this case they must be cut down to the floating, leaving 
only the margin formed by the running mould. This 
margin forms a bearing for the top end of the rule. In 
some instances a special margin or bearing is cut at the 
outer members of running moulds for cornices and skirt- 
ings, and when run they form a bearing for the floating 
rules. 

When ready for the finishing coat, empty as much as 
required of neat Parian cement into a clean banker, and 
gauge it smooth and stiff; then soften it down to the 
desired consistency, always bearing in mind not to make 
it too soft, as sloppy stuff for any purpose is ever to 
be avoided. The gauging should be so arranged that 
when one batch is in use another one is ready, which 
prevents delay in laying the whole space, thereby ensur- 
ing similarity of texture and results. The thickness of 
the finishing coat should not exceed % inch. When 
there are about a dozen yards laid, two men must follow 
on and rule the surface fair from screed to screed on 
ceilings, and top and bottom on walls. The greatest pos- 
sible care must be observed that the whole surface is 
ruled in fair and uniform, otherwise the surface will be 
imperfect. 

White cements, owing to the suction of the walls or 
ceilings, have a tendency to shrink more or less, accord- 
ing to the stiffness of the gauge and the section, there- 
fore they must be ruled in twice. When the coat already 
laid is firm, then some more cement, gauged softer than 
the first, should be laid thinly all over, and ruled as care- 
fully as before. Having done this the whole surface is 



TERMS AND PROCESSES 137 

nearly ready for scouring. It is allowed to stand for an 
hour or two, or until quite firm. If scouring is at- 
tempted before, it will work into hollows, and a bad job 
will be the result. If the finger cannot make an im- 
pression upon it easily, it is sufficiently firm, and then 
all hands begin to scour the work, using very little water, 
and working the hand float with a circular m^otion. The 
hand float must not be worked long on one spot, but kept 
moving over all the surface within reach, and working 
back again until the whole surface has an even grain or 
texture. The whole work must be scoured twice to bring 
it up to a fine solid surface. When there is about half 
of the wall scoured, two or more plasterers can continue 
the scouring, and the remainder of the men go back and 
start the trowelling. This must be done with good long 
strokes, using very little water, and taking care not to 
dent the surface with the trowel. After the men have 
finished the scouring, they come back and start at the 
beginning with the second '^ trowelling off" or final 
trowelling. This is done both vertically and horizon- 
tally, and when the work begins to harden, the trowel is 
laid on the near edge and worked with a cutting motion 
downwards. This is repeated all over the work until 
every particle of glut or ' ' fat ' ' is cleared off the surface. 
If the work has to be polished, the cutting action with 
the trowel must be followed with a 9-inch joint rule and 
a damp brush, but the work must be hard before this 
last can be attempted. Work carried out on the above 
plan will reflect credit on the material and the workers. 
The same methods apply equally to Keen 's and Martin 's. 
Martin's is preferred by some plasterers for running 
cornices because it sets quicker than Keen's. For plain 
surfaces, such as walls and ceilings, it sets too quick, 
and has to be "killed" (that is working the stuff again 



138 CEMENTS AND CONCRETES 

and again with water until the initial set is stopped or 
"dead") before it can be conveniently used. Although 
it finally sets fairly hard, it never attains the same de- 
gree of hardness as Keen's or Parian. 

Several other white cements and plasters have been 
introduced during the last two decades. They will be 
noticed later on. 

White Cement Efflorescence. — For work that has to 
be painted, care must be exercised in the selection and 
manipulation of the materials used for the plaster work, 
so as to avoid as far as possible subsequent efflorescence. 
In the manufacture of Keen's, Parian, and Martin's 
cements, Keen's original process is doubtless the best. 
It requires, however, great care in carrying out, the 
chemicals used and temperature employed requiring to 
be suited to the peculiarities of the gypsum. The de- 
sired result is extreme hardness, combined with non-ef- 
florescence. Keen's cement is practically non-efflores- 
cent, as if applied on a dry wall containing, no soluble 
salt, in itself there would be no efflorescence that would 
spoil paint. Perhaps one should not say that Keen's 
cement, or at least all brands of it, are absolutely non- 
efflorescent, as there is generally a powdery coating comes 
on the surface, just enough to whiten a colored hand- 
kerchief, something like the coat of puff powder used 
on some female faces. On no account should Keen's 
cement be used on walls as a preventive of damp, as 
it is useless for this purpose. If used on a damp wall, 
or in places exposed to atmospheric influences, it will 
effloresce more or less, as its base is gypsum, which al- 
ways remains soluble. In damp situations the walls 
should be rendered or floated in Portland cement before 
the finishing coat of Keen's cement is laid. The same 
remarks apply to Parian and Martin's cements. The 



TERMS AND PROCESSES 139 

Keen's cement manufactured by Hunkin's and Willis, 
St. Louis, Mo., is practically non-efflorescent. 

Cornice Brackets. — Brackets or cores are used to de- 
crease the amount of materials and weight, and also to 
form a foundation and support for cornice or other 
mouldings. For large exterior work they are generally 
formed with stone, and for small work bricks, tiles, or 
slates are used, which are built into the walls as the 
work proceeds, and roughly fashioned to an approxima- 
tion to the profile of the intended cornice or other mould- 
ing. For interior work the brackets are sometimes con- 
structed with metal lathing, also with spikes and tar - 
bands, termed ' ' spike and rope brackets, ' ' but the oldest 
and most general way for cornice mouldings are "lath 
brackets." The "brackets" on which the laths are sub- 
sequently nailed are cut out of boards from % inch to 
11/2 inches thick, according to the size and form of the 
cornice. The section of the brackets should be about 1 
inch less than the profile of the proposed cornice to allow 
for a thickness of lath and plaster. The thickness of the 
plaster should not exceed 1 inch, or be less than i/^ inch. 
If too thick it is a waste of materials, and the undue 
weight is apt to pull or spring the laths from the brack- 
ets, and if too thin the stuff is apt to crack. The profile 
of the bracket need not follow closely that of the cor- 
nice, but a general or approximate outline of the most 
salient members followed. Any thin projecting mem- 
bers may be subsequently strengthened by means of 
projecting nails and tar-strings similar to a spike and 
rope bracket ; also by using extra hair and plaster in the 
roughing out stuff. Brackets for enriched cornices re- 
quire special notice. Unless a due allowance is made for 
sinkings for the thickness of the cast enrichments and 
a correct form of bed, there will be unnecessary trouble 



140 CEMENTS AND CONCRETES 

in cutting and hacking the lath work and brackets when 
the running of the cornice is commenced. There is a 
marked difference between the section of a running 
mould for an enriched cornice and that of a plain cor- 
nice, even if the profile of both are the same. To avoid 
mistakes of this nature the plasterer should supply the 
carpenter with a section of the brackets, taken after the 
bed of the enrichments are set out on the tracing of the 
proposed cornice. 

Skeleton brackets is a term applied to a method some- 
times used for coring out angles, to save materials where 
there are no brackets, and for small mouldings. This is 
effected by placing the mould in position and then fitting 
a piece of lath in a vertical position, and allowing a space 
of about % inch from the face of the lath to the nearest 
part or most prominent member of the mould. A mark 
is then made on the ceiling and wall at the top and bot- 
tom of the lath. Similar marks are made at the other 
end of the wall and ceiling, and then a line is struck on 
the marks, from end to end of the ceiling and wall, by 
means of a chalk line. The stuff which forms the parts' 
of the screeds inside the lines is cut away, dusted, wetted, 
and then a narrow strip of gauged coarse stuff is laid 
along the lines where the ceiling and wall screeds are 
cut, and the laths which have been previously cut to the 
length of the first or trial one are fixed vertically into 
the gauged stuff, keeping them apart as in ordinary lath- 
ing. They are further secured by laying strips of 
gauged stuff on the outward surfaces at the top and bot- 
tom ends. After the stuff is set, the cornice is run in 
the usual way. 

Cornices. — Cornices, either plain or enriched, are 
formed with a running mould cut to the profile of the 
intended cornice. The formation of cornices consists of 



TERMS AND PROCESSES 141 

constructing the mould, making the running screeds, 
fixing the running rules, running the cornice and mitring 
the angles, with the addition of fixing the cast ornament 
for enriched cornices. Cornices were formerly run in 
short lengths and in sections. Two, three, and even four 
moulds were employed for cornices that are now done 
with one. For large cornices, where the mould is diffi- 
cult or sluggish to run, or apt to jump, the bearings 
should be greased or brushed with soap or dusted with 
powdered black lead or French chalk. Running moulds 
are run in some places with the left hand, from left to 
right, and the mould plates are also fixed to the left hand 
side, having the bevelled part of the stock to the right 
or running side. In America the plates are fixed or the 
running or right side, and the mould is run with the 
right hand from right to left. The way of running from 
left to right with the left hand allows more freedom, 
especially in small mouldings, for the right or trowel 
hand to assist in feeding the cornice with the stuff that 
gathers on the mould. It also gives more freedom to 
his partner who is laying on the stuff, as with the hawk 
in his left hand and his trowel in his right he is able to 
work in a natural position, namely, from left to right, as 
in laying coarse or setting stuff on walls, whereas, when 
the mould is run with the right hand, and from right to 
left, the worker has not so much power or freedom in 
assisting to feed the mould with his left hand. His part- 
ner, who is laying the gauged stuff, is working back- 
handed, and if using a laying trowel, can only work from 
its heel instead of from the point as is usual; and if 
using the large gauging trowel for laying on every 
trowelful used must be put on with a backhanded turn. 
It may be a matter of opinion as to which method is 
better, and depends a good deal upon which way the man 



142 CEMENTS AND CONCRETES 

has been taught, but the manner of running the mould 
and laying on of stuff from left to right, the same as 
in writing, is the most natural. Running screeds are 
used as bearings for running moulds. They are com- 
posed of gauged stuff, and made straight with floating 
rules. Screeds for cornices are formed with raw or with 
gauged coarse stuff. They are next traversed. The 
line of the screed is got by placing the running mould 
in its true position or at one end of the wall, and mak- 
ing a mark on the floating screeds at the outside of the 
nib and the bottom of the slipper. The same operation 
is repeated at the other end of the wall, and a continuous 
line from one mark to the other made on the ceiling wall 
by means of a chalk line. A narrow strip of gauged 
putty and plaster is now laid on the lines by one man, 
while his partner follows on with a traversing rule, work- 
ing the rule with a slanting motion, and moving back- 
wards and forwards until the screed is just and true. 
"Where the walls are verv long, runnins- screeds are done 
by two men w^orking a long straight edge or floating 
rule. The screed is afterwards further fined by draw- 
ing a cross-grained hand float three or four times over 
it in a longitudinal direction. Where the coarse stuff 
screeds are not gauged, the running screeds are made in 
a, similar manner, but the putty is mixed with an equal 
proportion of setting stuff before gauging. The addi- 
tion of sand gives more resisting power to the wear of 
the nib and slipper of the running mould. The run- 
ning screeds are made on the long sides of the room, 
and when set they give a bearing for the end screed in 
its true position at one end of the wall. 

Fixing the running rules is the next operation. This 
is done by placing the running mould in its true position 
at one end of the wall, taking care that the mould is 



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TERMS AND PROCESSES 143 



a 



square," that is, that the perpendicular parts of mem- 
bers are plumb with the wall. This may be tested with 
a plumb bob hanging over the side of the mould, and by 
seeing that the line of the plumb bob hangs properly over 
a marked line which has been previously made by squar- 
ing off from a square member or by extending a parallel 
line from an upright member of the mould. When the 
mould is plumb and square, a mark is made on the ceil- 
ing screed at the outside part of the nib, and another 
made on the wall screed at the bottom of the slipper. 
The same operation is repeated at the other end of the 
wall, and the line extended from mark to mark by using 
a chalk line. The line in this case should be blackened 
by means of charcoal or burnt stick, as it shows better 
than a white line on the light-colored screeds. As the 
chalk line may sway when striking the wall line, this 
line should not be trusted for fixing the running rules 
to. This may be proved by placing the mould every 3 
or 4 feet apart in the length of the wall, taking care to 
keep the outer edge of the nib at the ceiling line; then 
marking with a gauging trowel at the bottom of the slip- 
per. Nails are now driven into each of these marks and 
left projecting as a guide for fixing the running rules. 
The running rules should not be less than 2i/^ inches 
wide or more than 3i/2 inches wide and % inch thick, 
being made out of good redwood or pine planed on both 
sides and edges. The ruJes are now fixed into the wall 
screed either by nailing them to the studs or into the 
joints of the walls. They are also fixed by wetting one 
face of the rule. and laying dabs of gauged putty and 
plaster about two feet 6 inches apart. The rules are 
now pressed on the wall while the stuff is soft, taking 
care not to force the guide nails out of position. The 
rules are further secured by laying patches of gauged 



144 CEMENTS AND CONCRETES 

stuff underneath the rule partly on the wall and rule 
where the dabs are. When the rules are fixed by nail- 
ing, it is apt to crack the first-coat of floating, and the 
joints of the wall are not always easily found. The 
coarse stuff for the first-coat of cornice brackets should 
be extra haired and carefully scratched to give a strong 
foundation for the following coats of gauged stuff, which 
in many instances is extra thick at bold or projecting 
parts of the mouldings. 

For large moulding and wire lathing it is best to leave 
the brackets uncoated when first coating the general 
work until the cornice running is commenced, and then 
to rough out the whole cornice from the lath work with 
gauged coarse stuff. This gives uniform suction and 
strength. If the brackets are lathed with wood, they 
should be first-coated with gauged coarse stuff and 
scratched before the screeds are formed, so as to allow 
time for the lath work to settle before the mouldings 
are roughed out. Weak laths frequently twist by mcist- 
ure from the first-coating, and gradually settle or re- 
sume their origmal form during the drying of the first- 
coating. Leaving the lathed brackets uncoated also 
forms a vent for the moisture from the w^all and ceiling 
first-coating, thus allowing it to dry sooner. The ccarse 
stuff for roughing out the cornice should be gauged uni- 
formly in strength and consistency, as unequal gauging 
tends to cause unequal sAvelling in the material, conse- 
quently the mould is more difficult to run true. The 
coarse stuff should be laid regular in thickness, taking 
care to gradually build up and fcrm all thick parts and 
projecting members with the trowel to prevent the stuff 
from dropping and the mould from dragging it off, as 
generally happens if the stuff is laid in thick and irregu- 
lar coats. When roughing out large mouldings with 



TERMS AND PROCESSES 145 

coarse stuff, the members of the mitres should also be 
filled in and ruled fair before the running with gauged 
putty is commenced, because when mitrmg, it will be 
more easily and quickly done, materials will be saved, 
and when finished, the whole will be more uniform in 
color. 

When all the mouldings are roughed out, the plaster 
muffle or muffle plate, as the case may be, is taken off, 
and the running with fine gauged putty commenced. 
The gauge board and all tools should now be cleaned to 
free them from grit. A ring of putty is formed on the 
gauge board, leaving the bottom of the board clear; 
water is put in the ring and the plaster quickly and 
evenly sprinkled over the water, taking care not to sprin- 
kle it on the putty ring. The plaster and water are 
mixed together by stirring with the point of a trowel. 
The putty is then quickly mixed with the gauged plaster 
by using the trowel and turning it over with the hawk. 
It is put on with a large gauging trowel, or if the mem- 
bers are large, with the laying trowel, following the form 
of the mouldings. The mould is then run along by one 
man, who also feeds the moulding with any stuff that 
may gather on the side of the running mould. This 
operation is continued until all the members of the 
mouldings are filled out. A thin gauge of fine putty, 
having less plaster than the previous gauges, is lightly 
drawn over with a trowel, or brushed over the flat mem- 
bers, and thrown with a brush for small or dry mem- 
bers. This mould is then quickly and steadily run along 
the cornice from beginning to end and finished. If the 
moulding is extra large in girth, or a long length of 
moulding has to be run, extra men are required to lay 
the stuff, while two may be necessary to run the mould. 



146 CEMENTS AND CONCRETES 

"When running small mouldings, say of 10 or 12 inches 
in girth, one man can run and feed the mould while his 
partner is laying on. When all the mouldings are run 
around, the running rules are taken down, the screeds 
cleaned and scraped, and any holes or defects caused 
by nails or patches used for the rules made good by fill- 
ing up with gauged putty. If soap, black lead, or any 
other materials already mentioned are used to aid and 
ease the running of the mould, they should be scraped 
off with a drag as soon as the cornice is run off, other- 
wise they will prevent the finishing coats for wall and 
ceiling from adhering to those parts. 

To Set Out and Construct Corinthian Entahlature. — 
To enable the plasterer to set out a full size or working 
drawing from the architect's design, also to comprehend 
the cornice and the architrave, which are sometimes used 
alone or as separate mouldings, their proportions with 
that of the entire entablature are given. The entabla- 
ture and the details of the enrichments of the coffers 
and modillions are shown on plate. 

The whole height of the entablature is divided into 
ten parts, giving three to the architrave, and three to 
the frieze, and four to the cornice, as shown by the first 
upright scale at Fig. 1. This figure shows the combined 
section and elevation of the entablature. The height 
of the architrave is subdivided into five parts to form 
its members, as shown by the second upright scale. 
Projection is taken from the lower fascia, and is equal 
to one-fourth part of its height. As the cornice of the 
Corinthian order is frequently used alone as a separate 
moulding, an enlarged view with figured details is given, 
see illustration Fig. 4. It is necessary that the details 
of the cornice should be mastered before proceeding with 
the entablature. See Plate 1. 



TERMS AND PROCESSES 147 

"With regards to the enrichments of the entablature, 
as shown in Fig. 1, the whole must be set out and so dis- 
posed and arranged that the centre of each will be in line 
with each other, or, in other words, that they are regu- 
larly disposed perpendicularly above each other, as 
shown from A to B (Fig. 1) where it will be seen that . 
the centres of the modillion, dentil, egg, and other bed- 
mould enrichments are all in one perpendicular line. 
Enrichments set out in this v/ay are said, in plasterers' 
parlance, to ' ^ principle. ' ' Nothing is more careless, con- 
fused, and unseemly than to distribute them without 
any order or principle, as they are in many buildings. 
The centre of an egg answers in some places of the cor- 
nice to- the edge of a dentil, in some to the centre, and 
in others to the space between, all the rest of the enrich- 
ments being distributed in the same slovenly artless 
manner. The larger parts must regulate the smaller. 
All the enrichments in entablatures are governed by the 
modillions, or mutales, and distribution of these must 
depend on the interval of the columns, and to be so dis- 
posed that one of them may come directly over the centre 
of the column, as shewn in the present example at C 
(Fig. 2), the axis of each column. 

The enrichments must partake of the character of the 
order they enrich. When the frieze is enriched, and the 
enrichment may be characteristic of the order, or it may 
serve to indicate the use of the building, the rank, quali- 
ties, profession, and achievements of the owner. Hav- 
ing set out the profile and the enrichments, making the 
running mould and the running mouldings now claims 
attention. For large work the cornice and the archi- 
trave are run separately, the cornice being run from the 
slipper screed made on the frieze and a nib screed, and 
the architrave from a slipper screed made on the wall 



148 CEMENTS AND CONCRETES 

and a nib screed made on the frieze. Sections of the 
cornice and architrave running moulds are shown at 
Fig. 4. 

It may be here remarked that the nib and slipper 
bearings of the cornice and architrave running moulds 
are made for work on ceilings and walls ; but if the 
entablature projects or is independent, and supported by 
columns, the nib of the cornice mould must be cut so 
as to bear and run on a nib running rule fixed on the 
weathering of the cornice, and the slipper of the archi- 
trave running mould cut so as to bear and run on a 
running rule fixed on the sofiit of the architrave. The 
frieze, if plain, is set by hand; and if enriched, a bed 
for the enrichment must be made by running a small 
part of the bed at the top and bottom of the frieze when 
running the cornice and architrave mouldings. In this 
ease the screed on the frieze must be set back to allow 
for the plate or ground of the ornament, and the nibs 
and slippers of the running moulds extended at these 
parts. In setting out the mould plates an allowance 
must be made for the bed of the various enrichments, as 
previously described. 

The profiles of the three largest enrichments are indi- 
cated by the dotted lines. The angles of the beds of 
these enrichments are splayed, as shown, to save fine 
plaster used for the cast work. This also strengthens 
the top member of the architrave while it is being run. 
It will be seen that an in-dentil is used in this cornice, 
as shown by the dotted line at 1 on the elevation. This 
is the space between the face or main dentils. The in- 
dentil is run with the mouldings, and the dentils are cast 
and planted. The in-dentil and the dentil may also be 
cast together in short lengths, and then planted. In 
this case the running mould must be cut to form a bed 



TERMS AND PROCESSES 149 

for the combined dentils, as indicated by the dotted line 
on the outside of the section of the running mould. The 
dotted line on the section of the running mould shows 
the section of the main dentil. In some examples the 
external angles of the bed of the dentils are filled in with 
an ornament fashioned like a cone or pineapple, instead 
of using an angle dentil. An enlarged view of this class 
of ornament fixed in position is shown at Fig. 11. The 
bed of the small enrichments is made square as shown. 

When setting out the mould plate, the profile of the 
soffit of the corona must be taken through the centre of 
the sunk panel, as shov/n by the shaded part at Fig. 3, 
thus forming the raised part of the mould as shown at 
Fig. 4. 

The most intricate part in the construction of a Cor- 
inthian cornice consists in the formation of the coffers, 
as shown at Fig. 2. This is a plan of the cornice at an 
external angle. F is a coffer, and M is a modillion or 
* 'block," as it is commonly called. The coffer consists 
of a sunk panel, with an enrichment on the four sides, 
and a rose or patera in the centre as shown. A section 
of the coffer is shown at Fig. 3. The coffers are formed 
by fixing a ''style," as from S to S (including the side 
enrichments), on the sunk panel, so as to connect the 
two run plain sides of the soffit and form two sides of 
the coffer. The lines in the front and back of S and 
S indicate the joints of the style before they are stopped. 
It will be understood that the style is fixed before the 
block is fixed. A plan of the complete style is shown at 
Fig. 5. When making the model of the style, the side 
enrichments must be set out mitred and fixed on the 
plain part of the style, and a perforation made in the 
centre to act as a key for the fixing stuff used when 
fixing the block. A mark must also be made in the cen- 



150 CEMENTS AND CONCRETES 

tre of the front of the style to act as a guide when fixing 
the styles. The model of the style is moulded in wax, 
taking care to splay the back and front edges and the 
centre perforation, also the mitres of the enrichments, 
to allow the mould to draw in one piece. These parts 
are trimmed square after the styles are cast. Having 
fixed two styles, the front and back parts of the coffer 
enrichments, as shown at Fig^s. 6 and 7, are fixed; then 
the patera (Fig. 8) is fixed; and then the joints of the 
styles are stopped, which completes the coffer. This 
done, the block (Fig. 9) is fixed, and then the small en- 
richment (Fig. 10) is fixed, thus completing a part of 
the soffit of the corona. The other parts are of course 
made and fixed in a similar way, but the positions of 
the coffers and blocks must be set out on the whole 
length of the cornice before the fixing is commenced. 

Setting out coffers and blocks is a simple matter, yet 
it requires care to ensure accuracy. First fix a coffer 
and a block in each mitre, as shown at the external 
mitre (Fig. 2) ; then from the centres of these blocks set 
out the whole length of the cornice. This is best done by 
measuring the full length of the cornice from the mitre 
blocks, and dividing the total by the combined width of 
one modillion and a coffer, and if there is no remainder, 
the combined width is marked on the soifit ; but if there 
are a few inches over, they are divided among the given 
number of blocks. The marks are proved by going over 
them with a compass or a wood gauge. When the exact 
positions of the centres of each coffer with the block is 
ascertained, the marks are extended across the corona 
and down the plain member on which the back end of 
the block rests on by the aid of a square. These ex- 
tended marks or lines give the centres for fixing the 
styles of the coffej's and the blocks. Fixing the coffers 



TERMS AND PROCESSES 151 

and the blocks is the next part of the process. This 
being done, as already described, taking care to use the 
centre mark on the coffer as a guide for fixing it fair with 
the centre lines on the soffit, and using a wood square to 
prove the square of the style, also using the edge of the 
square to prove the level of the coffer with the run sides 
of the soffit, then clean off any excess stuff that may 
exude at the keyhole and edges of the style. After this 
the back and front side enrichments are fixed, as already 
mentioned. Before fixing the paterae a keyed or under- 
cut hole must be cut in the sunk panels to give a key for 
the stuff that is used for fixing the paterae. A corre- 
sponding keyed hole must also be formed on the back 
of the paterae. This is best done by making the desired 
size of sinking in the model of the paterae before it is 
moulded. These sinkings must be undercut after the pa- 
terae are cast. 

The model of the paterae is generally moulded with a 
front and back waxed mould. For large paterae, or those 
having a deep projection a piece of twisted galvanized 
or copper wire, sufficiently long to enter the keyed holes 
in the paterae and the soffit, should be inserted in the 
fixing stuff when fixing the paterae. This method should 
always be adopted where the bedding surface of the pa- 
terae is small, so as to enable it to resist the weight of a 
brush while being painted or gilded. If the paterae are 
extra deep, and project below the line of the soffit, they 
should be fixed first, otherwise they are liable to get dis- 
turbed when fixing the blocks and other enrichments. 

The modillions should be fixed with stiff gauged stuff 
for the keyed holes in the styles, and the corresponding 
holes in the blocks (which are made while being cast), 
and using softer gauged stuff for the bedding surface of 
the block. After the fixing stuff is laid, place the block 



152 



CEMENTS AND CONCRETES 



in position, and work it gently but quickly from right to 
left, so as to force the excess stuff out, and obtain a true 
and solid bed, taking care that the centre of the block is 
linable with the centre mark on the soffit, and using a 
square to prove the squareness of the block, and then 
clean off the excess stuff. The small enrichments (Figs. 
6, 7, and 10) are fixed with soft gauged stuff, so that 
they can be easily and quickly fixed. Small cast work 
of this kind should always be fixed with soft gauged 
stuff, as there is very little weight to carry until the stuff is 
set. The suction alone between the two bodies is often suf- 
ficient to support the cast until the stuff is set. These small 
enrichments are moulded with a face or front wax mould. 

Modillions or blocks were 
formerly cast in three parts, 
namely, the body, the main part 
of the leaf, and the tip or curled 
end of the leaf; the body being 
cast in a wax piece mould (some- 
times a plaster piece mould) , and 
the leaf and its tip in a front and 
back wax mould, but now the 
complete block is generally cast 
in one piece in a gelatine mould. 
The body of the block may be 
cast in a gelatine mould, but 
where the back section of the leaf is clear or away from 
the block near the scroll end, as shown in the accom- 
panying illustration, and seen in fine old buildings, the 
leaf should be cast and fixed separately. An enlarged 
view of the plan and side elevation of a modillion is 
shown in illustration No. 5. The bed moulds and the 
other small enrichments in the entablature are generally 
cast in wax moulds. 




Modillion. 
NO. 5. 



TERMS AND PROCESSES 



153 



When fixing the enrichments in an entablature, take 
special care that they all "principle" with each other 
as already mentioned, thus forming a pleasing and artis- 
tic finish, which is characteristic of well-designed mould- 
ings. 




-Corinthian Cornice. 
NO. 6. 



To Set Out a Corinthian Cornice. — The members 
which are enriched in the <?ornice, shown in the preced- 
ing plate, are drawn as plain members on this cornice so 
as to show the profile and method of setting out more 
dear. 



154 CEMENTS AND CONCRETES 

The combined elevation and profile of the cornice 
shown at Fig. 1, in the accompanying illustration, No^ 6, 
is an enlarged view of the cornice of the Corinthian en- 
tablature. The first upright scale contains four parts of 
the ten into which the whole entablature is divided, as 
on the preceding plate. The second scale is divided into 
five parts, the third of which goes to the modillion, the 
fourth to the corona, and fifth to the cymatium ; the first 
and second together are divided into three parts, the first 
for the reversed cyma at the bottom, the second for the 
dentils, and the third for the ovolo. The smaller mem- 
bers are in proportion to the greater, as shown by the 
smaller divisions on the scale. The modillions are 1-6 
of the diameter of the column, and their distances two- 
sixths and a half. Half a diameter is divided on the 
corona at Fig. 2 into six parts, of which the width of the 
modillion is two, and the length of it is four. The cap 
projects 1-3 of those parts, and the distance between the 
modillions is five. By this rule the exact distance from 
centre to centre of the modillions is 7-12 of the diameter. 
The dotted line A C answers to the diminished part of 
the column, from whence the cornice is projected; the 
projection being equal to its height, is divided into four 
parts, as shown by the scale at the bottom of the cor- 
nice. One-fourth of this scale is divided into six parts, 
as shown at C, five of which gives the width of the modil- 
lion. The distance between them is in proportion to it 
as figured at Fig. 2. The fillets, F F, of the modillion 
are % of its width, and so is the bead, B. The position 
and size of the sunk panel are indicated by the dotted 
lines in the corona at Figs. 1 and 2, the size being ob- 
tained as shown by the figures in the dotted spaces. The 
width of the dentils, D, is obtained by dividing the semi- 
diameter of the column marked on the corona at Fig. 2 



TERMS AND PROCESSES 155 

into fourteen parts, two of which gives the width of the 
dentil, and one the space between them. This space of 
course is also the width of the in-dentil^ the height of 
which is one-fourth of the height of the main dentil, as 
indicated by the small division on the inner side of the 
second upright scale. 

The centres and radius for describing the profiles of 
the cymatium or cymarecta, the ovolo, and the inverted 
cyma or ogee members are indicated by small crosses and 
dotted lines. 

Mitring. — Mitring is looked upon by the generality of 
plasterers as a test of speed and ability. As they gener- 
ally work in pairs on other portions of the work, their in- 
dividual ability is not easily seen, but when mitring a 
man carries the operation through alone. Mitring being 
done by hand, is a near approach to modelling, and is an 
operation of which a dexterous and good plasterer is nat- 
urally proud. The quality and time required for mitres 
greatly depend upon the degree of hardness of the run 
cornice, also upon the suction. A mitre can be more 
freely worked and more expeditiously done on a hard 
cornice surface, and where there is a suction. The extra 
absorbing powers of brick walls as compared to lath par- 
titions cause the gauged stuff to get firm sooner, and 
enables the mouldings to be more readily blocked out be- 
fore the stuff is set. A common error when mitring is 
gauging the stuff stronger than that which has been used 
for the running of the cornice, causing extra swelling 
and difficulty of ruling the members over, and cutting 
the run part of the cornice with the joint rule, especially 
if the stuff sets before the plasterer has had time to rule 
all the members over, and then being stronger, and con- 
sequently setting quicker, he has not so much time for 
forming the members. Ordinary sized mitres can be 



156 CEMENTS. AND CONCRETES 

done with one gauge by using less plaster than in the 
gauge for running the cornice, and stiffening the greater 
portion with dry plaster, and using this for roughing out 
the mitre; then using the soft portion left for brushing 
over the members and filling up all holes, and afterwards 
working the joint rule over the metal to take the su- 
perfluous stuff off. Should the mitre not be fine enough, 
the gauged stuff can be further softened on the hawk by 
adding water, and working it with the gauging trowel, 
hrushing the soft or creamy stuff all over the mitre 
again, then working the joint rule again. Small mem- 
bers, and those at the top and bottom of the cornice, 
where there is most absorption, should be worked by the 
joint rule first, leaving the large members, drips or coves, 
or where there is a large bcdy of stuff, to be ruled over 
last. The joint rule should always be Avorked horizon- 
tally, especially when dealing with beads and carvettos. 
Drips and large members should be worked with the 
joint rule with an upright motion, because if worked 
down, the stuff may be pulled down. Mitres should not 
be worked, fined, or tooled with small tools, as they can 
and should be brought to a good and straight surface 
by the proper use of the joint rule. Small tools should 
only be used for laying the stuff when required, and 
cleaning out the i itersections of the mitres, quirks, and 
for stopping. A square-ended small tool may be used 
for smoothing flat, straight surfaces. Returned mitres 
and short brealvs are "run down," then cut to the re- 
quired lengths and planted. They may also be mitred 
by hand. 

Mitre-Mould. — Various attempts have been made to 
construct a running mould that would form the mitres 
simultaneously with the cornice running. Most plasterers 
will have heard of, and some may have tried to make 



TERMS AND PROCESSES 



157 



and work a mitre-mould to save hand labor. Those who 
have tried it will have found the results far from satis- 
factory. The subjoined illustration. No. 7, shows the- 
method of setting out and constructing a mould intended 




-Mitre-Mould. 

NO. 7. 

for forming the moulding and mitres in one operation. 
The mould is made by fixing the metal plate at an angit 
of 45 degrees on the slipper, or in other words fixing the 
iron plate at one angle of a square slipper, which allows 
the mould to run nearly up to the angle, one face of the 
slipper being used for one side of the wall, and the othei 



158 CEMENTS AND CONCRETES 

face at right angles being used for the other side of the 
wall. Fig. 1 shows the method of setting out the profile 
of mould. A is a given section of a moulding, and B 
is the section of the moulding at the mitre. To obtain 
this, first draw the moulding A full size, and then extend 
the ceiling line and draw another wall line. Then from 
the projection of the top member draw an angle line at 
45 degrees. Carry up the projections of the various 
members to the angle (or mitre line) and then draw" hori- 
zontal lines from the various members ; also centre lines 
of large members as from a to 1 (the vertical letters). 
Take off the lines a to 1 (diagonal letters) on the angle 
line, and set them on the ruling line from a to 1 (hori- 
zontal letters), and then laying them down to the hori- 
zontal lines, the intersections give the profile for the 
mitre-mould. Fig. 2 shows a side elevation of the mitre- 
mould, and Fig. 3 shows a front elevation. It will be 
seen that the mitre-mould is an expensive and unsatis- 
factory fad. The time expended in setting out the elon- 
gated members, making an extra mould, and cleaning 
out the intersection by hand ( as the mould does not leave 
a finished mitre), also making good the parts broken by 
drawing out the mould from interlocked or undercut 
members in the moulding, is not repaid. An average 
plasterer would put in all the mitres of an ordinary 
sized room while the mould was being made. The mould 
will only run into every second angle, and must be taken 
off and reversed to fit the next. It may seem a waste of 
time and space to describe and then show the utter use- 
lessness of a mitre-mould, but having met many plas- 
terers who stated that they had used or had seen a mitre- 
m.ould that worked wonders, I am constrained to give a 
description, not only to save future futile controversy, 
but to show that in this book the much-debated trade 



TERMS AND PROCESSES 159 

subject has not been omitted. In concluding this sub- 
ject, it may be stated that not any one of the mitre-mould 
plasterers would or could practically explain the modus 
operandi of this mysterious m.ould. 

Fixing Enrichments. — Enrichments should be fixed 
straight, square, plumb, and firm. Cornice enrichments, 
such as bed moulds, friezes, &c., for which a bed or sink- 
ing to receive them is formed by the running mould, do 
not require such strong gauges stuff as soffits, medallions, 
or other hanging casts. For light enrichments the gauged 
putty and plaster should never be stronger than that 
used for the cornice, and clean strong size water should 
be used. This gives more time for fixing a number of 
casts, and improves the cementing force. The bed for 
the cast work should be scratched, dusted, and wetted 
before the cast work is applied. A small portion of fine 
plaster (the same as used for casting the enrichments) 
should be gauged with clean size water, to be used for 
the joints. The gauged fixing stuff should be spread 
evenly over the back of the cast and over the scratched 
bed of the moulding. No more should be laid on than 
will fully fill up the scratches. Then place a small piece 
of the white 'or joint gauge on the point, and press the 
cast into position by gently but quickly sliding the cast 
twice or thrice backwards and forwards to expel the air 
and incorporate the two bodies. It is a mistake to dab 
a lump of gauged stuff at random on the back of the cast 
and press it on the bed, as the stuff does not properly 
enter the scratched part of the bed, and the contained 
air prevents proper cohesion and solidity. When too 
thick a coat of stuff is laid on the coat, straight and even 
fixing is more difficult. The excess stuff oozes out at the 
sides, and unless time and care be taken in cleaning it 
off, the moulding, or cast, or both, get damaged. A 



160 CEMENTS AND CONCRETES 

small portion may also ooze out in the first method, but 
it will be so thin that it can be brushed off while soft. 
When fixing medallion blocks or trusses, a dovetailed 
hole should be cut in the vertical and horizontal parts of 
the bed, and similar holes in the blocks (which are made 
when being cast) are filled in with gauged stuff and 
applied in position. If the cast should be very heavy, 
or of Portland cement, it is further secured by inserting 
a slate or iron dowel while the stuff is soft, allowing a 
portion of the dowel to project to enter into the body of 
the cast. Heavy casts should be temporarily supported 
by wood props until the fixing stuff is set. When fix- 
ing heavy casts the plain surface of the plaster work 
should be cut as far as the lath to obtain a better and 
stronger key. The putty in the fixing stuff should be 
mixed with long strong hair or tow, as described for rib 
mouldings or ceilings. Hair or tow may also be used 
advantageously in fixing Portland or other cement work. 
Cast work, w^hen extremely heavy, should be further se- 
cured by means of long screws or bolts, placed so as to 
pass through the cast work and into the timber, the 
casts being bedded with gauged haired stuff and tem- 
porarily propped up. The screws or bolts should be 
fixed before the stuff is set to a^'oid the probable dis- 
turbance of the gauged bedding. Before fixing any cast 
work they should be placed in position to prove their 
correct fitting. Centre, side and end lines should be 
made on the surface of the bed to give a guide for fix- 
ing. It may be necessary to fix nails at intervals in the 
lines to give a further guide. 

Mitring Enricliments. — Before fixing continuous or 
space cast w^ork, the length and width of the panel or 
room should be set out to prove that the mitres are equal- 
sided, balanced and have flowing lines. Nothing looks 



TERMS AND PROCESSES 161 

so slovenly or unworkmanlike as a mitre in an ornament 
cut haphazard, with the leading stem disjointed or 
springing out of a flower or tendril. If the design is 
vertical, say a bed mould or frieze with an alternate leaf 
and husk, what can be more offensive to artistic taste 
than a part of the leaf on one side and a part of the 
husk on the other side of the mitre ! There is no ex- 
cuse for this want of taste and wanton treatment. A 
little time expended in setting out the work will obviate 
these defects. Where there are no shrinking and stretch- 
ing casts the mitres can be eased by stretching or shrink- 
ing the, cast work at the joints. Stretching or shrinking 
are evils, and it depends on the design of the enrich- 
ments which of the two is the lesser, but in most instances 
shrinking is the greater evil. Shrinking does not require 
so much labor to make the joints good. Stretching does 
not show quite so much, especially if the joint is well 
modelled and of the same color. It also gives greater 
scope and freedom. It has already been mentioned that 
in good shops the breaks or other short lengths are set 
out in the shop and that there are stretching and shrink- 
ing casts and mitres modelled and made to facilitate the 
formation of good mitres. This latter method is cer- 
tainly the cheapest and most satisfactory in the end. The 
setting out is best done by cutting a lath as a gauge to 
the length of the cast and marking the length of each 
cast temporarily on the bed of the cast work from mitre 
to mitre. When the mitre has been determined on and 
the casts set out to come in, the marks are made more 
distant to give a guide for fixing each separate cast as 
required. It is better to measure thrice than alter twice. 
Space ornaments should also be set out accurately, but 
there is no difficulty in the mitres, as the intervening 



162 CEMENTS AND CONCRETES 

space between each cast can be increased or diminished 
as required. 

When fixing medallion blocks, dentils or paterae, the 
mitres should be fixed first and then the spaces and posi- 
tions set out. Special care must be taken when mitring 
enrichments with distinctive vertical parts, such as fig- 
ures, or pendants of flowers, or fruit in friezes, that the 
cast work is not unequally or irregularly scratched so as 
to enable them to come to an equally balanced mitre at 
the angles. Where there are no stretchers the cast work 
should be cut between the main vertical parts, so that the 
joint on each side will be equal, or, in other words, that 
the vertical parts will be equidistant from the main or 
other parts when fixed. The same remarks apply to 
shrinking. The mitres of running enrichments, such as 
soffits, etc., are made up with bands or ribbons,, which 
are cast or worked in situ by hand. The latter way is 
the quickest and most artistic. Another plan is to fix 
paterae or drops at the internal and external mitres. 
The scroll work of the enrichment is then formed to 
spring from the paterae and finish at the patera at the 
next mitre. Sometimes the inner member at each side 
of the soffit is worked across at right angles at each mitre, 
thus forming a small square sinking or panel, which is 
then filled in with a patera or drop. 

Bed moulds, such as an egg and dart, have internal and 
external mitre leaf modelled and cast. This is a neat 
and quick way of forming mitres. A good cornice, with 
well-modelled and efi^ective ornament, may be disfigured 
and spoiled by careless mitring, yet it is as easy (and in 
many cases more so) to make good and satisfactory 
work. It is therefore best to set out correctly and make 
sure of a correct finish before beginning to fix. Illustra- 



TERMS AND PROCESSES 



163 



tion No. 8 shows the method of mitring various forms 
of fret enrichments. 

Pugging. — Pugging or deafening is a body of plastic 
materials laid on boards fixed between the joists of a 
floor, or lath and plaster partitions. It is intended to 
prevent sound and smells from passing from one room 
to another. Pugging is generally performed by laying 
a thick coat of coarse stuff on a foundation of rough 
boards on fillets, which are nailed on the sides of the 
joists. Chopped hay, straw or ferns, mixed with lime, is 




■^Fret Ornaments, showing their Mitres. 
NO. 8. 

sometimes used for the plastic coat. Coarse plaster with 
and without reeds is also used in some districts. Saw- 
dust is sometimes substituted for reeds. Pugging may 
be done by forming a foundation with thick rough lath 
wood. On this a coat, about % inch thick, of coarse stuff 
is laid, and when dry a layer about 2 inches thick of dry 
ashes or lime riddlings is deposited on it. The upper sur- 
face is then sprinkled with water and finished with a coat 
of coarse stuff. This makes sound-proof work, but in the 



164 CEMENTS AND CONCRETES 

event of subsequent damage or alterations the dry ashes 
run out, causing further dust and damage. In some in- 
stances the dry ashes are gauged with lime. When laid 
the upper surface is beaten and smoothed with a shovel. 
This makes sound-proof and durable work, impervious to 
vermin. Partitions are deafened by lathing between 
the studding and then laying on a coat of coarse stuff. 
When dry the partition is lathed and plastered in the 
usual way. Pugging slabs of fibrous plaster are now 
largely employed. They have the advantage of being 
light and dry and are rapidly fixed, 

Sound Ceilings. — No lath and plaster ceilings can be 
made sound and free from cracks unless the joists are 
well seasoned, firmly fixed and sufficiently strong to 
carry the overhead weight, as well as sustain the weight 
of the lath and plaster, and resist jarring. Ceiling joists 
should never be more than 12 inches apart from center 
to center. Where double lath is used the joists may be 
14 inches from center to center. Good laths, with break 
joints every three feet, and well nailed, are also impera- 
tive. If the above dimensions are exceeded the laths 
are liable to give or twist on account of the weakness of 
the laths or the weight of the plaster, or both com- 
bined. If the joists exceed 2 inches in the width they 
should be counter-lathed or strapped to ensure a key for 
the plaster. Where it is impracticable or inconvenient 
to fix the ceiling joists so close they should be brand- 
ered. This strengthens and stiffens the joists, also gives 
a free key for the plaster and forms a sound, level ceil- 
ing. 

Brandered or strapped ceilings are done by nailing 
wood straps or fillets across the under sides of the joists. 
The fillets are from 1% to 2 inches square and are fixed 
from 12 to 14 inches from centre to centre. The sizes 



TERMS AND PROCESSES 165 

and distance apart varies according to the thickness of 
the lath and the class of plaster work. Brandered ceil- 
ings are largely used in some places and make good 
sound ceilings. 

Cracked Plaster WorU. — Cracks in plaster work are 
due to various causes. They may act individually or in 
combination. Cracks are often caused by settlement in 
the building. These cracks may be easily discerned by 
their breadth, depth and length. They also arise from 
the shrinkage of bad or unseasoned timber used in the 
construction or framing of the building, which may 
cause displacement in the joists or the laths. Cracks 
are sometimes caused by the laths being too weak, or by 
too much plaster being laid on weak laths, or too little 
plaster laid on strong laths. Other causes are the too 
sudden drying of the work, strong winds or heat, che 
laying of one coat of mortar on another coat, or on walls 
that have a strong suction which absorbs the moisture or 
'4ife" of the coat being laid, when it becomes short, or 
crumbly, scaly and apt to peel or fall off. In this last 
case it does not set, but only dries and shrinks, which 
gives rise to cracks, and eventually falls or crumbles 
away. The use of bad materials, insufficient use of lime 
and hair, or scamping of labor is often followed by 
cracks. Insufficient labor and unskilled workmanship in 
the application of the materials is a great source of 
trouble, but it will be understood that the best quality 
of labor will not make bad materials good and strong; 
and, on the other hand, the best materials will not com- 
pensate for bad labor. It is only by judicious selection 
of materials and their skillful manipulation that a high 
and enduring class of work can be obtained. 

Repairing Old Plaster. — Repairing is also termed 
patching, " * ' j obbing ' ' and ' ' making good. ' V "When 



It 



166 CEMENTS AND CONCRETES 

repairing or making additions to old plaster work, care 
should be observed in cutting the joints so that the key of 
the existing work is not injured or broken. The joints 
one way should be cut on the studding or joists and in 
a line with the laths the other way. A joint at the edge 
of a lath is stronger than at the center. If the lath work 
is weak the joints should be cut diagonally. Never use 
a hammer to cut joints on lath work, for the repeated im- 
pacts will weaken and crack the old work. If the old 
plaster is hard, cut the joint with the saw or with a ham- 
mer and chisel and finish with a strong knife. Avoid 
acute angles in patches. Square, round or oval patches 
not only look better but are much stronger than zigzag 
ones. Having cut the joints neat and square on edge 
and then repaired the old lath work, brush the joints 
and the laths with a dry broom and then wet the joints, 
but only dampen the lath work, as excessive water tends 
to warp the laths. The joints are sometimes painted to 
prevent damp from extending to the old work or caus- 
ing injury to any surface decoration. Gauged coarse 
stuff is generally used for roughing out and gauged putty 
for finishing ordinary work. The coarse stuff is gen- 
erally gauged with coarse plaster. For small patches 
the whole thickness is generally brought out in one coat, 
but for large patches it is best to lay a first coat and 
then scratch it in the usual way. If time permits this 
should stand for one day, or even two, to allow the lath 
work to settle. The stronger and stiffer the gauge, the 
less power the laths will have to warp. The floating coat 
is gauged moderately stiff with coarse plaster or with 
fine plaster and coarse in equal proportions. 

When laid, the surface is ruled in with a straight- 
edge, keeping it within the line of the old work to allow 
for plaster swelling and a thickness of 1-16 inch for the 



TERMS AND PROCESSES 167 

finishing coat. It is often necessary to drag the surface 
down to allow the finishing coat to be ruled fair and 
flush with the old work. The surface should be left fair 
but rough. Gauged work should never be scoured, as it 
only kills the plaster, and therefore weakens the body of 
the material. The putty for the final coat should be 
gauged with fine plaster and a little size water. After 
being laid the surface is ruled flush with the old work, 
and when firm it should be smartly trowelled off and 
finally finished with a semi-wet brush. The joints should 
be trowelled flush and smooth and the old part brushed 
to free it from any gauged stuff. All rubbish should be 
damped as it falls, and removed as soon as possible to 
prevent further dust and dirt. 

Parian or other white cements are used for best work, 
or where time is a consideration. All white cements 
having plaster for their basis are manufactured to be 
non-efflorescent, non-porous, durable, free from liability 
to unequal shrinkage (which causes cracks), and free in 
working. They form admirable materials for repairs or 
additions. When making good old or broken lime plaster 
work with any of these cements, the joints and lath nails 
must be painted with red lead, quick drying paint, or 
with shellac. Galvanized nails ought to be used for the 
lath work where these cements are to be used. Small holes 
and cracks are usually stopped with fine plaster gauged 
with putty, or better still, putty water. Parian cement is 
also used for a similar purpose. The holes and cracks 
should be brushed with Parian solution before the stiff 
Parian is applied. This solution is simply fine Parian 
gauged to a thin creamy consistency with water. New or 
damp lime-plastered walls can be painted or papered 
much sooner, and with greater safety, if brushed with a 
thin Parian solution. It is also useful for stopping the 



168 CEMENTS AND CONCRETES 

suction on dry floating and fibrous slabs before laying 
the final coat. Several of the new patent plaster and 
white cements are well adapted for repairs, or where 
time is limited. 

Gauged Wo7'k. — All gauged work should be regulated 
in strength according to the purpose required. A brick 
or stone wall would not require so much plaster as a lath 
partition. "Work not subject to friction or wear does not 
require so much plaster. If the work is required for 
immediate use, as with running screeds, or blocking out 
large mouldings, or fixing large castings much plaster 
must be used. The amount of plaster required for scaf- 
fold work varies from ^ to equal proportions for gaug- 
ing coarse stuff or setting stuff, and from 1-3 to equal 
proportions for coarse stuff for heavy cornices, and 1-3 
to equal proportions for putt}^ and fixing ornament. The 
amount of plaster also depends upon the quality of the 
plaster, some of which are much stronger than others. 
Coarse plaster that is of a dark and sandy nature is gen- 
erally weak, sets quickly, and becomes soft and useless. 
Fine plaster should be used for gauging putty when run- 
ning cornices, also for fixing enrichments. All gauged 
work should be gauged with uniformity, each separate 
gauge having the same amount of water and plaster as 
required for the bulk of stuff being gauged. Unequal 
gauging causes hard and soft places in the work, and 
when more plaster is used in one gauge than another 
there is an extra expansion caused by the swelling of 
the plaster, which makes the work more difficult to do 
when fioating, setting, running mouldings, or mitring. 

A quart and a pint measure should always be kept on 
the scaffold for measuring the water used for the vari- 
ous gauges. The quantity of water will regulate the 
quantity of plaster for each gauge. A proper plaster 



TERMS AND PROCESSES 169 

box should also be on the scaffold, made to hold a sack of 
plaster, and having a lid made in two halves hinged from 
the centre. This prevents the plaster from getting dirty 
by falling stuff, and from getting damp by absorption 
from the atmosphere. Where there is a large quantity 
or continuous gauging, the box should be placed on a 
stand (this is called a stand-box) to prevent unnecessary 
exertion and loss of time by stooping for each handful. 

When gauging coarse stuff for large surfaces which 
require several gauges to complete the work in hand, size 
water should be used in proper proportions with the neat 
water used for gauging, so as to allow sufficient time to 
properly manipulate the material. In the event of 
gauged stuff setting before the work is laid and ruled off, 
it is difficult to make the surface strong and fair. This 
also allows the various gauges to be laid on or against 
the previous ones while they are in a soft state, thus 
forming stronger joints and better cohesion between the 
various gauges. The use of size water in gauged set- 
ting stuff and putty enables the work to be freely trow- 
elled and finished. Gauged stuff should not be hand- 
floated, as excessive working destroys the setting powers 
of the plaster. 

Joist Lines on Ceilings. — Common flat ceilings show 
in time the precise position of the joists above, and in 
many instances the position and form of the lath work 
can be easily discerned. Many theories have been ad- 
vanced as to the cause of these unsightly lines or marks, 
which are so distressing to the mind and eye. In my 
opinion they are due in a great measure to insufficient 
material and inferior work. The plaster which is be- 
tween or separate from the joists is more pervious to the 
atmosphere than that which is in more direct contact. 
The air in passing through leaves behind it particles of 



170 CEMENTS AND CONCRETES 

dirt assigned in larger measure to the unattached than 
to the attached portions. Dust that finds ingress be- 
tween the joints of flooring boards lies on the unattached 
portions, consequently the joists show themselves as 
lighter lines on a more or less dirty background. The 
same causes apply to the lines on. the lath work. An- 
other cause is that the plaster work is too thin. In many 
instances the floating is brought up from the lath in one 
coat. This is a most pernicious habit, as it is not only 
the cause of lath lines, but the ceiling invariably cracks, 
and develops spontaneously original patterns indicative 
of rivers, which too often lead like Niagara to a catas- 
trophe in the form of falling plaster. Joists and lath 
lines on thin ceilings may be partly obviated by laying 
strong bro^^m paper over the upper side of the lath and 
plaster and then pasting the edges to the sides of the 
joists, so as to form a cover to the plaster work. The 
better and most sanitary way is to lay the work in three 
coats, allow the first coat to dry^ consolidate the floating 
coat by well scouring with a hand float, and render the 
setting coat hard, non-absorbent, and impervious to the 
air by thorough scouring, trowelling, and brushing. 

EouGH Casting. 

Several years ago I was requested by the Editor of 
''Architecture and Building" of New York to prepare a 
short treatise on the subject of "Rough Casting" for 
publication in that magazine. The article was pub- 
lished in almost every architectural journal in the coun- 
try, and Mr. Kidder embodied it in his excellent work, 
''Building Construction and Superintendence, Vol. I." 
I reproduce it here, as the directions given therein have 
been found to be of the very best, and most workmen in 



TERMS AND PROCESSES 171 

this line of the trade adopt the methods of manipulation 
herein described. 

*' Rough casting, or, as it is sometimes called, slap 
dashing, both of which are synonymous with the French 
JiGurdage, rough work, and ravalement, having a similar 
meaning, is a method of plastering the outside of a build- 
ing much used in the northern part of Canada because 
of its being durable, cheap and well adapted to keep out 
cold winds during the long winters in that section of 
the world. The methods of applying rough cast and the 
mixing thereof do not materially differ from the meth- 
ods adopted in Northern Europe or even in the North- 
western States, but it is these minor differences, says a 
writer in an exchange, that make the Canadian rough 
casting superior, so far as durability is concerned, to 
much that is done in other parts of the world. 

There are frame cottages near the City of Toronto and 
along the northern shores of Lake Ontario that were 
plastered and roughcasted exteriorly over 40 years ago, 
and the mortar today is as good and sound as when 
first put on, and it looks as though it was good for many 
years yet if the timbers of the building it preserves re- 
main good. Rough cast buildings are plentiful in every 
province in the Dominion from Halifax to Vancouver 
and from Lake Erie to Hudson Bay, and when well built 
and the rough cast properly mixed and properly applied 
the result is always satisfactory. It is quite a common 
occurrence in Manitoba and the Northwest Territories 
in the winter to find the mercury frozen, yet this inten- 
sity of frost does not seem to affect the rough casting in 
the least, though it will chip bricks, contract and expand 
timber, and render stone as brittle as glass in many 
cases, and the effect on iron and steel is such as may 



172 CEMENTS AND CONCRETES 

prove dangerous if exposed to sudden and unexpected 
strain. 

In preparing a frame or log building for rough cast- 
ing care must be taken in putting down the founda- 
tion. A good stone or brick foundation is, of course, the 
best, but where rough casting is intended stone or brick 
foundations are seldom used because of their cost, and 
the builder is compelled to use posts of wood. The 
posts are generally made of white cedar, which has a 
lasting quality of 35 or 40 years if sound when used. 
The posts are put in the ground from 3 to 5 feet, the 
deeper the better, as they should be deep enough in any 
case to prevent frost from forcing them upward. When 
a sufiicient number of posts have been properly placed 
a line is struck on them a proper height from the ground 
and the tops levelled off. The sills are then placed — all 
joints being broken on top of posts — and the whole made 
level. These sills and all the other timber, scantlings 
and lumber should be well seasoned, if possible, for the 
greatest enemy to the plasterer is unseasoned timber; 
shrinkage of joists, posts and scantling not only breaks 
the bond of the mortar, but causes great cracks in cor- 
ners and angles that no amount of pointing or patching 
can ever make good. 

When the frame is up and the rafter on and well se- 
cured the whole of the outside should be covered with 
good, sound, common inch stock pine, hemlock, spruce, 
or other suitable lumber, dressed to a thickness. If put 
on diagonally so much the better, but this is not abso- 
lutely necessary if the rough casting is to be of the best 
quality, as will appear hereafter. 

When it can be done it is best to get all partitions set 
in place and lathed, the roof on and all necessary out- 
side finish or grounds put in placie and made ready to 



TERMS AND PROCESSES 173 

receive the lath. The carpenter must prepare his finish 
or grounds for finish to accommodate the extra lath, as, 
the walls will be thickened accordingly. 

For the cheaper sort of rough casting in one or two 
coats the following method of lathing is employed: Nail 
laths on the boarding — over paper or felt, if paper or 
felt is used — perpendicularly 16 inches from centre to 
centre if 4 foot laths are used, or 18 inches or 1 foot 
from center to center if 3 foot laths are used. The whole 
surface to be rough cast will require lathing this way. 
When done lath as is ordinarily done with No. 1 pine 
lath, breaking joints every 15 inches. Put 5 nails in 
each lath, driving each nail home solid, coat over with 
mortar, well haired, and that has been made four or more 
days; smooth and straighten as well as possible with a 
darby. When done and while yet soft the rough cast is 
thrown on it with such force as to drive the pebbles or 
small stones deep into it. The mixture or dash, as it is 
called, is composed of fine gravel, clean washed from all 
earthy particles and mixed with pure lime and water 
till the whole is of a semi-fluid consistency. This is 
mixed in a shallow tub or pail and is thrown upon the 
plastered wall with a wooden float about 5 or 6 inches 
long and as many wide, made of I/2 inch pine, and fitted 
with a wooden handle. While with this tool the plaster- 
er throws on the rough cast with his right hand, he holds 
in his left a common white-wash brush, which he dips 
into the rough cast and then brushes over the mortar 
and rough cast, which gives them, when finished, a reg- 
ular, uniform color and appearance. 

For this sort of work the following proportions will 
answer : To one barrel of prepared gravel use a quarter 
of a barrel of putty; mix well before using. This may 
be colored to suit the taste by using the proper materials, 



174 CEMENTS AND CONCRETES 

as given further on. It must be understood that the fore- 
going is the cheapest sort of rough casting, and is not 
recommended where more durable but more expensive 
work is required. 

The best mode of doing this work as practised in the 
Lake district of Ontario is nearly as follows. Have the 
frame of building prepared as indicated in the foregoing, 
with partitions all put in and well braced throughout and 
well secured. Lath diagonally with No. 1 pine lath, 
keeping 1% inches space between the lath. Nail each 
lath with 5 nails, and break joints every eighteen inches. 
Over this lath again diagonally in the opposite direction, 
keeping the same space between the lath and breaking 
joints as before. Careful and solid nailing is required 
for this layer of lathing, as the permanency of the work 
depends to some extent on this portion of it being honest- 
ly done. The mortar used for the first coat should have 
a goodly supply of cow's hair mixed in with it, and 
should be made at least four days before using. The 
operator must see to it that the mortar be well pressed 
into the key or interstices of the lathing to make it 
hold good. The face of the work must be well scratched 
to form a key for the second coat, which must not be put 
on before the first or scratch coat is dry. The mortar for 
the second coat is made in the same way as that re- 
quired for the first coat, and is applied in a similar man- 
ner, with the exception that the scratch coat must be 
well damped before the second coat is put on in order 
to keep the second coat moist and soft until the dash or 
rough cast is thrown in. The rough casting is done ex- 
actly in the same manner as described for the cheaper 
sort of rough cast work. 

A building finished in this manner, if the work is well 
done, possesses many advantages over the ordinary 



TERMS AND PROCESSES 175 

wood covered structure. It is much warmer being al- 
most air tight so far as the walls are concerned. It is 
safer, as fire will not eat its way through work of that 
kind for a long time. It is cleaner, as it will not prove 
such a harbor for insects. It may be made as handsome 
as desired, for before the rough cast is dashed it may be 
laid off in panels of any shape by having strips of bat- 
tens tacked over the soft mortar, which may be removed 
after the rough casting is done and the coloring finished. 
It is much superior to the so-called brick veneered house, 
as it is warmer, more exempt from fire and cheaper. 

For 100 yards of rough casting in the manner 
described the following quantities will be required : 1800 
laths, 12 bushels of lime, 1^/^ barrels of best cow hair, 
1% yards of sand, % yard of prepared gravel and 16 
pounds of hot cut lath nails, 1^/4 inches long. The gravel 
should be sifted through a % i^ch mesh screen, and 
should be washed before mixing with the lime putty. 

To color 100 yards in any of the tints named herewith 
use the following quantities of ingredients : For a blue 
black mix 5 pounds of lamp black in the dash. For a 
buff use 5 pounds of green copperas, to which add 1 
pound of fresh cow manure ; strain all and mix well with 
the dash. A fine terra cotta is made by using 15 pounds 
of metallic oxide mixed with 5 pounds of green copperas. 
A dark green color is made by using 5 pounds of green 
copperas and 4 pounds of lamp black. Many tints of 
these colors may be obtained by varying the quantities 
given. The colors obtained by these methods are perma- 
nent; they do not fade or change with time or atmos- 
pheric variations. Many other colors are used but few 
stand like the ones named. A brick color may be obtained 
by the use of Venetian red and umber mixed in whisky 
first and then poured into the dash until the proper tint 



176 CEMENTS AND CONCRETES 

is obtained. In time, however, like all earthy pig- 
ments, these colors fade and have a sickly appearance; 
they answer better in cements than when incorporated 
with fat limes. 



VARIOUS METHODS OF RUNNING CORNICES, 

CIRCLES, ELLIPSES AND OTHER ORNAMEN- 
TAL STUCCO WORK. 

Diminished Columns. — The diminishing of columns is 
an interesting but somewhat difficult operation. Great 
care must be exercised not to overdo the entasis or swell- 
ing. The swell may commence very gradually from the 
base to the capital, or the third part of the column may 
be of the same diameter, and then swell and diminish for 
the remainder of its height. Two methods are here given 
to show how this may be done. These are given more 
to illustrate the method of setting out the diminished 
floating rulesi — so necessary to the plasterer — than to 
define the swell or diminishing of a column, which, being 
within limits a matter of taste, pertains more correctly 
to the architect. 

The best instrument for forming a diminished column 
(plain or fluted) is a diminished ' floating rule, with a 
cutting edge made to the contour of the proposed col- 
umn. This rule is used to determine the central posi- 
tion of the astragal and base mouldings (which act as 
bearings when ruling off the floating stufi: and the final 
coat), so as to obtain a true and uniform diminish, and 
also to form a fair surface. The appended illustration 
No. 9 elucidates the method of setting out diminished 
columns which is also used for setting out the diminished 
rule for both columns. The method for setting out a 
diminished rule for a column that diminishes two thirds 
of its height is as follows : The dimensions of the column 

1T7 



178 



CEMENTS AND CONCRETES 






=^ : — ^, • — • -rp 


:h>fl-4-£^-t::H^:-:H1- 


- -1 


r 


^SSE^: 


} 








k"' 


<< 


« 


•^ 


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^k 


I -' "^ 



METHODS OF WORK 179 

having been fixed, i. e., the height of the shaft and its 
upper and lower diameters, draw a perpendicular line 
which may be taken as the centre line of the column; 
then set out the upper and lower diameters, as shown in 
Fig. la. This figure also shows one-half of the con- 
structural brick work, and the plaster, which is dis- 
tinguished by being dark shaded with the floating rule 
in position. A floating rule for forming the curved and 
diminished surface requires an iron plate, similar to a 
mould plate, as shown, so that it will cut the stuff off 
cleaner and truer, and last longer. The other half of the 
elevation shows the lines and divisions for obtaining and 
setting out the entasis. 

To diminish the column, first divide the height into 
three equal parts then at the lower third (5) draw a 
semicircle equal to the lower diameter of the column. 
Next divide the upper portion of the column into four 
equal parts, as shown at 1, 2, 3 and 4, then draw a line, 
parallel with the axis or centre line of the column, from 
figure 1 at the top of the column, cutting the semicircle 
at 1, divide the remainder of the semicircle into four 
equal parts, which gives the diminishing points. From 
these points draw lines parallel to the axis of the column, 
and from the corresponding figures, or from 2 to 2, and 
so on. In these intersecting points fix pins or nails, and 
bend a flexible strip of wood or metal round the nails, 
and draw the curved line. The whole line from top to 
bottom is then transferred on to the board that is to be 
used for making the floating rule. This column will have 
its greatest diameter for one-third of its height, and the 
upper portion its entasis. This method is so far defect- 
ive as to require the curve to be drawn by hand, a de- 
fect, however, obviated by using a column trammel, 
which is used for a column that diminishes with a grace- 



180 CEMENTS AND CONCRETES 

fill curve from the base to top of the shaft. This trammel 
is made as follows: 

Column Trammel. — A column trammel is simple in 
construction, and when carefullv used oives verA' satis- 
factory results, forming a graceful diminished curve 
from the lower diameter to the upper diameter of the 
shaft. Before describing the method cf setting out and 
constructing the column trammel, the method of finding 
the poini D on Fig. 2 is gh-en on a separate sketch (Fig. 
5) to show the method more clearly. 

Fig. 5 illustrates the method of obtaining the point D, 
on which the centre pin is fixed for the trammel to 
slide on while working. This point also gives the length 
of the radius-rod. This sketch is reduced one-half in 
size to that of Fig. 2a. but the letters correspond to it. 
Having set out the axis or centre line of the column (A 
B) and the base line (A C) (extending the latter indefi- 
nitely) as described for Fig. la, proceed as follows. From 
A as a centre, and from A to B as a radius, describe an 
arc, as indicated bv the dotted line: then frcm the in- 
tersecting point at C as a centre^ and from C to the 
point at B as a radius (as indicated by the dotted line), 
describe an arc until it cuts the base line at K. This 
done add the distance from the point at A to the point 
at K to the base line, outward from the point at C, which 
gives the desired point D. 

The trammel should be set out on a wall or a clean 
floor. To set it out. first draw a line to the exact height 
of the proposed column, as A B on Fig. 2a, then draw 
a line (indefinitely in length) at right angles to A B, as 
shown from A to D. This line A B is the axis or centre 
line of the column, and the line A D is the base line. To 
construct the trammel, take tAvo rules, each the length of 
the column, and about 2 inches wide, and fi^ in. thick; 



METHODS OF WORK 181 

fiy one on each side of the axis of the column, taking care 
to keep them equidistant and parallel to the axis, and 
forming a grooved space about 2 inches wide, as shown 
at a, a, the rules, and b the groove. These rules are 
made thicker than the board intended for the floating 
rule, so as to allow the trammel pencil to run freely 
when marking the diminished line on the board. This 
is shown by the section at Fig. 1. This is as when done 
in a temporary way on a floor, but a better way is to 
fix the rules on a board (a flooring board will be found 
suitable). This makes a permanent groove, and forms an 
easy ground for the sliding block to work smoothly. It 
also allows a greater space for a thicker beard for the 
floating rule. 

Fig. 2 shows enlarged details of the groove rules (A, 
A,) the groove (b,) the sliding block (B), with the pin 
(H), the radius-rod (F), with the pencil (G), and the 
board for the floating rule (C), with the diminished 
line. Fig. 1 shows a section, of Fig. 2. The letters in 
all figures correspond with each other. Fig. 2a shows 
the whole column with the trammel and finished floating 
rule (C). Make the radius-rod about 2 inches wide, 1 
inch thick and in length a little longer than the distance 
from D to B, and the half diameter of base of the shaft. 
The sliding block (H) is about 4 inches long and equal 
in depth and width to that of the sliding groove (b). It 
should be made smooth, and fit the groove easily, so that 
it will slide freely from end to end when working. In 
the exact centre of the block fix a hardwood pin or a 
round nail (H). This must be fixed exactly over the 
axis of the column, and so fitted that it will run imme- 
diately over it from end to end. Bore a hole in the ra- 
dius-rod to fit this pin, then from the centre of the pin 
set off exactly half the diameter of the base of the col- 



182 CEMENTS AND CONCRETES 

umn on the radius-rod, which will give the point for 
the pencil hole (G). At this point bore a hole large 
enough to receive a pencil, which must be tightly held in 
it. At the lower end of the radius-rod cut a slot just 
wide enough to receive the center pin at D. 

A plan of the radius-rod with the slot and centre pin 
is ishown at Fig. 3 and a section at Fig. 4. The block 
beneath the radius-rod, in the section is used to keep the 
rod level with the rules and sliding block, as shown on 
Fig. 1. To ascertain the length to cut the slot, place the 
radius-rod along the line A D, and the pencil at the out- 
side of the semi-diameter at the base of the column, and 
slide it to its place; mark on the rod where the centre 
pin (D) comes; then place the pencil end of the rod at 
the top diameter, and mark the rod again at the centre 
pin; this will give the length of the pin. Having made 
the trammel, provide a stout board to form the floating 
rule (cc). This board should be planed on both sides 
and one edge. Place it near the rtiles a a, keeping the 
planed edge outwards, and parallel with the axis or 
centre line of the column. This allows the planed edge 
of the floating rule to be used as a straight edge to 
plumb by when fixing the top and bottom rims or mould- 
ings, which are used as guides and bearings when float- 
ing the column. Place the sliding block in position, and 
lay the radius-rod over the center pin, and the pin of the 
sliding block, keeping the rod in a line with D A, tak- 
ing care that the pencil is in its true position ; then care- 
fully move it upwards, and pressing the pencil gently 
upon the board which will give the line for cutting the 
diminishing floating rule. The floating edge is strength- 
ened by nailing a strip of sheet iron on the board in a 
similar way to that in which a mould plate on a running 
mould is treated. This is of special use when floating 



METHODS OF WORK J 83 

diminished fluted columns or pilasters, as the thin and 
sharp edge allows the flutes to be more easily formed. 
The diminished line on the metal plate can also be 
formed with the trammel. 

A column trammel can also be used for setting out 
other diminished floating rules for columns less in size 
than the original one. The only alteration required for 
this purpose is to alter the point D to suit the size of the 
proposed column, and the shortening of the radius-rod. 
It will be seen that the floating rules for both columns 
are made long enough to bear on the base and necking 
mouldings, but it is usual to make them shorter so as to 
bear on cast or run rims or collars, which are fixed at 
the top and bottom of the shaft. 

Constructing Plain Diminished Columns. — Plain 
diminished columns and pilasters are formed with a 
diminished rule fashioned at both ends to work on the 
necking and base mouldings (termed rims), or on collars. 
The method of making rims and collars, which are used 
as bearings, is as described for diminished fluted 
columns. 

To Set out the Flutes of Diminished Column. — The 
annexed illustration No. 10 elucidates the method of set- 
ting out the flutes of a column. Fig. 1 shows the half 
plan of a column ; A is the plan of the flutes a'b the base, 
and B the plan at the top of the shaft. Fig. 2 shows the 
elevation of the column, with the various parts marked. 
Fig. 3 shows the plan and centres for setting out the 
flutings for the different orders with arrises or with fil- 
lets. A fluted column may be divided into twenty, 
twenty-four, or twenty-six flutes, according to the style 
or order. There are two different sorts of flutes used. 
One is worked to an arris, and sunk down in different 
depths, one of which is described by the fourth part of 



184 



CEMENTS AND CONCRETES 




P UAtM 

-Diminished Fluted Columns. 
NO. 10. 



METHODS OF WORK 185 

the circle, one by the sixth, and others by the half 
circle, as shown at C, D, E, Fig. 8. 

The square or fillet of the second kind is equal to one- 
third part of the flute. It will be seen in Fig. 2 that 
two lines are shown at the top of tlic flutes. The lower 
one shows how the flutes finish, when the fourth and 
sixth depths are taken, and the top line when the half- 
circle is taken together with the fillets. Flutes that 
finish with an arris are usually employed for columns in 
the Doric order, and those that finish with fillets are used 
in the other orders. The fillets or lists at the top and 
bottom of the shaft of a column, which serve to divide 
the shaft from the capital and base mouldings, are com- 
monly called the upper and lower fillets, and sometimes 
the horizontal fillets, but in architecture they are known 
as ' ' cinctures. ' ' The curved parts at the top and bottom 
of the shaft which are usually curved into the upper and 
lower fillets by a concave curve or inverted cavetto, are 
in architecture termed ' ' apophygis. " 

Constructing Diminished Fluted Columns. — The 
formation of diminished fluted columns by means of a 
running mould is an absorbing and vexed topic among 
plasterers, and many ingenious plans have been advanced 
for the construction of hinged and spring running 
moulds, and diminished running rules. I have known 
more than one self-improving plasterer who has ex- 
pended a vast deal of time and lime (not forgetting 
plaster) to prove by actual practice the possibility of 
running a diminished fluted column, while others have 
been content to work them by theory, forgetting that an 
ounce of practice is worth a ton of theory. Some men 
thought they had accomplished a feat when they had 
run a single flute with a hinged mould, between two run- 
ning rules fixed to form diminution in width, forget 



186 CEMENTS AND CONCRETES 

ting or not knowing that flutes diminish in depth as well 
as width. 

The difference in depth of flutes, at the base and the 
top of the shaft, is shown at A, the base, and B, the top, 
in Fig. 1, illustration No. 10. Running moulds have also 
been made with springs to regulate the diminish in 
depth, but their action was uncertain, and they are also 
too expensive for the purpose. Another form of run- 
ning mould was made by fixing wire, catgut, or leather 
on one end of one of the slippers, and on the upper edge 
of the stock, so that the slipper, when being forced up 
the diminished space between the running rules, became 
more angular, or in other words, the slipper on which 
one end of the wire was attached was higher up the 
diminished space than the other slipper, and thus caused 
the stock to cant forward, or be drawn out of an up- 
right, and reduce the depth of the flute. The stock in 
this case is connected to the slippers not by hinges, but 
by a pivot inserted at each slipper to allow the stock 
to cant forward when pulled by the wire. This form 
of mould also proved to be too erratic in its working 
to be of useful service. Running moulds having the 
stock connected to a slipper at each side by means of 
two hinges (termed a double-hinged mould) allow the 
mould to assume an angular or slanting form as it passes 
up the diminished space, thus forming a diminution in 
the width of flute, but it does not form it with a true 
arc all the way. On the contrary, it assumes an elliptical 
form which becomes more and more pronounced as it 
reaches the top of the shaft. 

The nearest approach to perfection in running dimin- 
ished flute is performed by means of a running mould 
made with hinged slippers as described, but having the 
mould plate and stock cut through the centre of the 



METHODS OF WORK 187 

profile, the two parts being then connected by a hinge. 
This form of running mould (termed a '' triple-hinged 
mould") allows the mould to collapse in the form of a 
V on plan, and the slippers to run level or parallel with 
each other, thus forming each half of the flute alike, and 
at right angles from the centre. Still this has the defect 
of forming the flute without the necessary decrease in 
depth. 

A method for diminishing the depth of the flutes is to 
make the running rules with a diminish on face, or 
rather to make them with an increasing thickness towards 
the top ends, so that the mould when running up on the 
increasing thickness will form a corresponding de- 
creased depth of flute. When running a fluted column 
by this process, the running rules are fixed flush with 
the face line of the fillets. Only one flute can be run at 
a time, but twelve may be in hand at the same time. As 
there are generally twenty-four flutes in a column, 
twelve rules would be required to keep a couple of 
plasterers going. When the fi^^st set of flutes are run, 
the rules are taken off and fixed to run the remaining 
flutes. When all are run, the returned ends at top and 
bottom require to be made good. It will be seen that the 
running rules for this method must be carefully made 
and fixed to ensure true lines and forms. It will be 
understood that a bed or ground must first be formed 
as a guide for setting out and fixing the running rules 
on. This is done with the aid of a diminished floating 
rule. It will also be self-evident ^hat the floating rule 
would be more profitably employed for forming the 
entire shaft with the flutes, thus dispensing with run- 
ning rules and hinged moulds. This method of running 
the flutes is slow and tediouSj but tne worst part is that 
the flutes are not true segments ; in tact, the whole of the 



188 CEMENTS AND COXCRETES 

methods mentioned are more or less a rule of thumb, un- 
certain and inaccurate. 

A knowledge of the rudiments of geometry will prove 
that the true form of a diminished and swelled fluted 
column cannot be run with a mould, however ingeniously 
made. This may be proved by cutting a plaster or card- 
board disc to the former radius of a single flute, and de- 
scribing a line round it on a board. This would be the 
form the mould, when at right angles at the bottom of 
the shaft, would give the flute. Then place the disc in 
an oblique position (the same as the hinged mould would 
be at the top), and project the plans by means of a set 
square on to the board. It will be seen that the mould 
would give the flute an elliptical form. It may be 
further explained by stating that when the mould is 
square at the base, or at right angles with the vertical 
running rules, the form of the flute would be a true 
segment; but when the mould is moA'ed up the dimin- 
ished space between the rules, it assumes an oblique or 
slanting position. It gives the flute an elliptical form, 
which increases and becomes more pronounced as it ap- 
proaches the necking. It may be said that the pointed 
or elliptical defects can be filled in and worked fair 
with circular hand floats, but this plan necessitates a 
series of hand floats to fit the ever-var^flng widths and 
depths of the flutes. 

It mav seem unnecessarv to describe the above meth- 
ods, and then to point out their defects. However, the 
methods and defects are given to prevent the rising plas- 
terer falling into the same errors, and to enable him to 
resist and rebut the arguments that are so often ad- 
vanced by some men, who persistently assert that their 
own particular way (genera-lly one of the methods al- 



METHODS OF WORK 189 

ready mentioned) is the correct and only way of proper- 
ly performing this different but interesting operation. 

It is worthy of note, to show the interest taken in 
this subject that a patent was obtained for a running" 
mould and process for forming diminished fluted col- 
umns, in 1878, which obtained a provisional protection 
for "improvements in moulds or templates for running 
stucco or cement tapered fluted columns." The follow- 
ing is a copy of the specificaticn in extenso : — 

This invention relates to the running of stucco or ce- 
ment in forming fluted or other columns, pillars, or pi- 
lasters, and similar surfaces, in a mere simple, economi- 
cal, and expeditious manner than heretofore; and the 
nature and novelty of the invention as applied for run- 
ning or making the body part of a fluted tapered col- 
umn of stucco or cement, consisting in constructing a 
short box-shaped template, having two sides joined to- 
gether by a back plate outside, with a handle upon it, 
for drawing it up and down the column, and with an 
open space inside the back between the sides open above 
and below, equal to any desired section or segment of 
the column at its base or widest part, into which the 
column is equally divided by narrow longitudinal 
strips of wood, against which the inner edge and end 
surfaces of the sides of the template slide close, so as to 
prevent the escape of the semi-liquid or stucco. A thin 
elastic segmental mould plate is hinged or jointed at its 
ends to the inner faces or edges of the template, formed 
in its inner scraping edge to correspond to the segmental 
curve of the base of the column, with rounded pro- 
jections corresponding to the flutes to be formed on the 
column. This plate and its hinges are laid at an angle 
highest at the inner scraping edge, and inclined down- 
wards towards the back, leaving a space between it and 



190 CEMENTS AND CONCRETES 

the back for the free passage or escape of the super- 
fluous stucco or cement scraped off the column during 
the ascent of the mould along the column on its longi- 
tudinal shaping strips before mentioned. 

"^ ' The one end or side of the mould is made to slide or 
contract laterally in slots or other equivalent guides in 
the back of the mould frame as it ascends along the con- 
tracting or tapering longitudinal laths, the thin plate 
bending or yielding down in a curvilinear form on its 
Qnd hinges before mentioned, so as to bulge inwards while 
bending downwards^ and so contract the column in a 
nearly true radical and segmental form from the bottom 
to the top of the column, the angle at which the scrap- 
ing mould plate is set on its hinges determining this con- 
traction of the scraping centre edge of its segment radi- 
cally in a ratio corresponding to the contraction of the 
lengths of the segment and moving sides of the mould, 
which, for large moulds and columns, might be car- 
ried and drawn up by handles secured to the tops of 
the ends of the moulds with ropes led up and over pul- 
leys at the top of the column, thence down to the hand 
of the operators, so that the mould may be raised and 
lowered at pleasure to form the whole segment of the 
column from the bottom to the top in nearly as simple 
and efficient a manner as plain mouldings are at present 
run by the usual simple edge scraping moulds, one seg- 
ment being run after the other in succession until the 
column is finished. 

^ ' For plain or other forms of columns the inner scrap- 
ing edge of the mould plate is made to correspond to the 
tapered surface of the column to be formed plain, seg- 
mental, or fluted as desired ; and for flat, square, or polyg- 
onal columns, which do not require a segmental mould 
scraper, this would be made straight, either plain or 



METHODS OF WORK 191 

fluted, as desired on its scraping edge, and set horizontal- 
ly on its hinges, instead of at an angle as described for 
the segmental mould scraper for forming round col- 
umns; and this mould scraping plate in any case is pre- 
ferred to be made of thin elastic steel or tempered cop- 
per or brass, which would bend and contract the flutes or 
ridges on the surface of the columns or pillars, equally 
and proportionally to the' several parts of the column 
over which the mould is traversed. Although the mould 
or template has been described as made with only one 
of its ends movable laterally, it is to be understood that 
both ends or sides may be fitted so as to move in a 
similar manner to suit different kinds of work. 

This patent method would be better understood if it 
had been illustrated. No provision for diminishing the 
depth of the flutes is given in this method. The use of 
flexible metal for diminishing purposes cannot be relied 
on for accurate work. 

Another method for forming diminished fluted col- 
umns is thus performed : — Make a single flute in plaster, 
and use it as a mould for casting reverse flutes composed 
of fibrous plaster. After casting as many. reverse flutes 
as there are flutes in the proposed column, indurate them 
with litharge oil or paraffin wax. Casts of the necking 
and base, each with about 3 inches of the fluted shaft, are 
fixed on the brick core. The shaft is then laid with 
Portland cement (or other desired cement) and sand un- 
til within about one-third of the line of fillets, and 
while this stuff is still soft, take a reverse flute 
(previously oiled) and press it into position, using the 
cement flutes at the necking and base as guides for fix- 
ing, and using a diminished floating rule to prove the 
outline. Repeat this process until all the flutes in the 
column are filled with reverse flutes. The intervening 



192 CEMENTS AND CONCRETES 

spaces or fillets are then filled in with gauged cement 
until flush with the outer surface of the reverse flutes, 
and further regulated with the floating rule. When the 
stufl^ is set, the reverse flutes are extracted, and any de- 
fects in the flutes made good. On the care in flxing the 
reverse flutes and fllling in the flllets depends the success 
of this method. 

Diminished fluted columns are also made by casting 
two vertical halves, and then flxing them on the brick 
core. The halves are fixed by means of cement dots, 
which are laid on the core at intervals. (Corresponding 
dots are laid on the interior of the casts. The casts 
are then pressed on the core until the dots meet, and 
both halves are in proper position. The cast work is 
made solid with the core by pouring a thin and weak 
solution of cement and sand into an orifice at the neck- 
ing. 

The cement and sand should be mixed in the propor- 
tion of one of the former to five of the latter. This 
gauge has suflicient binding power and strength for this 
purpose, and is not liable to expand or contract in wet or 
dry weather. This process is useful for small work, and 
makes a good job when cleanly cast and neatly fixed. The 
necking with the capital and the base may be fixed be- 
fore or after the shaft casts are fixed, according to cir- 
cumstances. The shaft casts are best formed in a reverse 
casting mould. 

Another method of casting a diminished fluted col- 
umn is effected by making a reverse casting mould. Fix 
it round the core, and pour the gauged material in at 
the top of the necking mould. By using a reverse 
casting mould made with a plaster face and a wood back- 
ing, or a mould made in flbrous plaster, the whole 
column with the core can be made in one piece. Hoi- 



METHODS OF WORK 193 

low columns, composed of Portland cement concrete, 
can be made to carry any weight supported by a stone 
column, or one constructed with a brick core of equal 
diameter. Cast hollow columns are made by temporarily 
fixing a wood or fibrous plaster core tapered to one end 
to allow it to be withdrawn when the concrete is set. A 
rough wooden or a fibrous plaster hollow core is used 
when casting a hollow column in situ. The core in this 
case is left in. 

After many years' experience and observation on this 
subject, I am of opinion that the true form of a dimin- 
ished fluted column (composed in Portland or similar 
cement, and constructed in situ) is best obtained by 
hand, with the aid of cement rims or plaster collars 
and a diminished floating rule. Most plasterers will 
admit that what can be and is done in stone or wood, 
can be done equally well in cement or plaster. A plaster- 
er has one advantage, inasmuch as he can add as well 
as subtract when forming circular surfaces, whereas the 
mason can only subtract. The two methods hereafter 
given for forming diminished fluted columns by hand 
are simple, speedy, and accurate. They are on one prin- 
cipal, and each may be used as circumstances require: 
one is termed the ''rim method," and the other the 
' ' collar method. ' ' 

Forming Diminished Fluted Column hy the Bim 
Method. — First make models of the half circumferences 
of the astragal or necking and base mouldings, each 
having about 4 inches of the fluted shaft, as shown at 
Fig. 1, the plan and Fig. 2, the elevation, on illustra- 
tion No. 10. To make the models, cut a mould plate to 
fit each of the full-sized mouldings, and the required 
size of the shaft, and ''horse" them with radius-rods, 
and run a little over one-half of each circumference in 



194 CEMENTS AND CONCRETES • 

plaster, and then cut them to the exact half circumfer- 
ence. This done, set out the flutes, then cut them out 
and form the returned ends. The method of setting out 
the flutes on the ends of the models is shown on the plan 
at Fig. 1. A is the plan at the base, and B the plan at 
the top of the shaft. The returned ends of flutes are 
shown on the elevation, Fig. 2. Add the square plinth 
to the base, as shown on the plan at Fig. 1, which com- 
pletes the models. Piece mould the models in plaster, 
and then cast as many half astragal and bases as re- 
quired. The materials used for the casts must be of the 
same kind as intended for the shaft. The brick or core 
of the column is now cleaned and well wetted, and then 
the astragal and bases are fixed in position, using the 
diminished floating rule to prove if they are central, and 
the fillets linable with each other. Apply a plumb rule 
on the back edge of the floating rule to test if the astragal 
and base are concentrical and parallel with each other. 
When these half casts are fixed together on the shaft they 
are termed "rims." The intermediate space on the 
shaft is then filled in and ruled off with the diminished 
floating rule, using the rims as bearings and guides for 
forming the fillet line of shaft. 

The methods of forming a diminished fluted column 
by the "rim method" is further elucidated by the an- 
nexed illustration, No. 11. This shows an elevation of 
the brick core of a shaft with the astragal rim, A and 
the base rim, B, fixed in position. D is the diminished 
floating rule in position for floating the main or fillet line 
of the shaft. The method of using a diminished flute 
rule for the flutes is illustrated in the "collar method." 

A second diminished floating rule is required to form 
the back surface of the flutes. This can be quickly made 
by laying the first rule flat on the floor, and from this, 



METHODS OF WORK 



195 



with compasses, describe the back line of the flute on 
another board, which is afterwards cut to the desired 





iV}.VUUUvUv>>av.,,.M//)i;»A 




nMiiiniiiiiiiitiiiiiiiiitiiiii 




-Floated Fluted Columns, Kim Method. 

NO. 11. 



line. This rule is used as a long joint rule to form the 
flutes. The rule should be worked with uniform pres- 
sure, the man at the top working in unison with the man 



196 CEMENTS AND CONCRETES 

at the bottom, both working the rule with a circular 
cutting motion. The flutes are fined down by the aid of 
a small float semicircular in section. For extra large 
columns three floats should be used — No. 1 cut to the 
top section, No. 2 cut to the middle section, and No. 3 
cut to the bottom section. The length of the floats may 
vary from 5 inches to 7 inches, according to the height of 
the column. If the columns are required with a smooth 
surface, the flutes are worked as above, but the floats are 
covered with fine felt, leather, or rubber, and the sur- 
face finished smooth with short joint rules or with pieces 
of flexible busks. The cast parts of the shaft, to the 
fillet members of the astragal and the base, should be 
keyed with a drag, so that the whole shaft, from arris to 
arris of the astragal and base fillets^ can be fined, thus 
giving a uniform texture and cclor, and avoiding a sur- 
face joint of the cast work and the fined work. 

A modification of this method is as follows: — The 
lower horizontal fillet of the shaft and the base mouldings 
are cast separately, the fillet part being used as bear- 
ings for floating the shaft, as already described, and the 
base is fixed after the shaft is fined. This plan is useful 
for some purposes, such as for extra large columns, as it 
gives more freedom for working the shafts and the bases 
are not so liable to get injured while working over them. 

Running Diminished Fluted Column hy the Collar 
Method. — Run a plaster collar about IV2 inches wide to 
the diameter of the top horizontal fillet of the shaft. 
The thickness must be regulated according to the space 
between the brick core and the line of fillet. Cut this 
collar in halves and fix them on the brick core, keeping 
the under side in a line and level with the top of the 
proposed fillet of the shaft. Run another collar to fit 
the horizontal fillet at the base of the shaft, and fix the 



METHODS OF WORK 197 

upper side of this one level with the bottom edge of the 
fillet at base of the shaft. This done, make two plaster 
models of the flutes, one for the top and one for the 
bottom of the shaft, each about 3 inches wide, and in 
thickness according to the brick core, the diameter being 
taken about 1 inch above the returned ends of the flutes 
at the top and bottom of the shaft. These models are 
set out and made as described for the first method, but 
using plaster instead of cement for the casts. The plaster 
casts are fixed in position, and then the brick core is 
laid and ruled off, using the main diminished floating 
rule (and the plain collars as bearings) for forming the 
main contour or line of the vertical fillets, including the 
horizontal or top and bottom fillets of the shaft, and 
using the diminished flute floating rule (and the plaster 
models of the flutes as bearings) for forming the flut3s. 
This done, the fluted collars are cut out, the spaces filled 
in and ruled off, and the returned ends of the flutes 
are formed, and then the whole shaft is fined while the 
work is green. The fillet collars are then cut out, and 
the astragal and base mouldings are then fixed, thus 
completing the column. It will be seen that this method 
entirely dispenses with joints between cast and floated 
work on the shaft, and allows it to be fined in one opera- 
tion. 

The method of running diminished fluted columns 
with the aid of collars is further elucidated by the an- 
nexed illustration No. 12. A C is the top fillet collar, B C 
the bottom fillet collar, and F C and F C are the top and 
bottom flute collars fixed on the brick core of the column. 
D R is the main diminished floating rule in position for 
forming the main contour or fillet line of the column. 
This rule' is rebated at the top to allow for a bearing on 
the top as well as on the edge of the collar. This rule 



198 



CEMENTS AND CONCRETES 



also forms the profile of tlie top and bottom horizontal 
fillets, and the curved parts of the shafts below the top 
fillet and above the bottom fillet. F R is the flute 





Forming Fluted Columns — Collar Method. 

NO. 12. 

floating rule in position when forming tlie flutes. The 
ends of this rule as shown bear on the back surface of 
a flute as indicated by the dotted lines. A portion of the 
astragal moulding, A, with a part of the shaft is shown: 



METHODS OF WORK 199 

so a^ to indicate the position to fix the fillet collar, A C ; 
a portion of the base moulding, B with a part of the 
shaft, is also given to show the position of the bottom 
fillet collar, B. C. It will be seen that these collars form 
fair bed for the astra,gal and base mouldings, and when 
taken off they leave true joints as indicated by the ar- 
rows at A and B. 

A modification of the above methods for forhiing the 
fillets and flutes is effected as follows : — Fill in the spaces 
on the shaft between the collars in this method — or the 
rims in the former method — and rule them off with a 
main diminished floating rule as already described and 
when the stuff is firm but not set, the positions and forms 
of the fillets and flutes are set out on the floated surface, 
then the flutes are cut out by hand by means of gouges 
and drags, and afterwards fined as already described. 
This system is specially useful for small columns. 

For extra high columns it will be found difficult to 
vv^ork a floating rule to form the whole height of the 
column in one operation, in fact, for some columns to be 
seen in cities, which are 20 feet to 30 feet high, and 
even higher, it would be impossible to form them with 
one floating rule. It is therefore necessary to divide the 
column into two or more sections, and cut the floating 
rules accordingly. In this case two or more plaster col- 
lars about 3 inches wide, and made to the exact circum- 
ference of the column at the point of division, are re- 
quired. These collars are then temporarily fixed in posi- 
tion to act as screeds, and after the whole surface of the 
column is filled in and ruled off, the collars are cut out 
and the spaces filled in, and then the whole surface 
fined in one operation. Three or even more floats, as 
already described, are required for the fining of high or 
massive columns. 



200 CEMENTS AND CONCKETES 

Having now briefly reviewed the more , or less useful 
methods, and described some of the most useful and 
practical methods, the conclusion to be drawn is, that 
diminished fluted columns are best done by working 
them by hand, with the aid of diminished floating rules 
and cast or run bearings. This first or rim method will 
be found useful for many purposes; but the collar meth- 
od, with the addition of intermediate collars for extra 
high columns, is the best for general use. 

Diminished Fluted Pilasters. — Pilasters are said to be 
a Roman invention. They bear an analogy to columns 
in their parts, have the same names and standard of 
measurements, and are diminished and fluted on the same 
principals. When pilasters are placed behind columns, 
and very near them, they should not project above one- 
eighth of their diameter; but if they are frpm 6 to 10 
feet behind the column, as in large porticoes and per- 
istyles, they should project at least one-sixth of their 
diameter. When they are in a line with columns, their 
projection should be regulated by that of the columns. 
When pilasters are used alone as principals in composi- 
tion, they should be made to project one-fourth of their 
diameter to give regularity to the returned parts of the 
capitals. The process for forming pilasters is the same 
as for columns. 

Panelled Coves. — Large coves, segmental or elliptical 
on section, having their surfaces panelled with mouldings 
which spring from the back or above a W"all or main 
cornice, and finish at or intersect with a b^am or other 
moulding at the top or crown of the cove, require to be 
carefully set out and screieded. The floating is done 
from two horizontal screeds made at the top and bottom 
of the cove, and from these vertical screeds are formed, 
and then the intermediate spaces or bays are filled in » 



METHODS OF WORK 



201 



and ruled off witli a floating rule bearing on the vertical 
screeds. The horizontal screeds are easily made, but the 
vei"tical ones require special care to insure all being uni- 
form in section. These screeds are formed with a tem- 
plate cut to the desired section, and about 2 inches thick. 
For large coves they are made with three or more pieces 
of wood. The most correct and expeditious way of 
forming circular screeds is by the "pressed screed" 
process. 




Section of Cove Showing Pressed Screed Process. 

NO. 13. 



Pressed screeds are simple and expeditious in con- 
struction. They form accurate grounds for floating pur- 
poses and for running mouldings on circular surfaces. 
The method of forming pressed screeds and floating co^es 
is shown in the accompam^ing illustration No. 13. This 
shows the section of a cove with the main or wall cornice 
and the crown moulding. F is a nib rule used when 



202 



CEMENTS AND CONCRETES 



running the main cornice. To float this cove for the run- 
ning of vertical mouldings, first form the top and bottom 
horizontal screeds (A and B), then form the pressed 
screed. This is effected by temporarily fixing the 
template, G, or by one man holding it on the bottom 
screed, and another man holding it on the top screed, 
while a third spreads and presses the gauged coarse stuff 
until the space between the first coating and edge of the 
template is filled up, then drawing the trowel down each 
side of the template clears off any superfluous stuff. 




-Fig. I. Floating Coves. TiG. 2. Levelling Rule. 
NO. 14. 



The template, which has been previously oiled, is then 
removed, leaving a narrow, but true and smooth screed 
ready for working on. This method gives a truer 
screed, especially in elliptical or long circular screeds, 
than floating or working with a template, because if the 
template is not worked perfectly vei'tical, the curve of 
the screed is altered and not true. 

The subjoined illustration (No. 14) elucidates the 
method of forming the screeds for floating cove surfaces, 
also for floating segmental, elliptical, or any other form 



METHODS OF WORK 203 

of interior and exterior angles in coves. Fig. 1 shows a 
plan of the cove. The letters in this sketch correspond 
with those on the same parts in the section on illustration 
No. 13. The first coating and the various bays, after 
the screeds are made, are indicated by crossed diagonal 
lines at the D's. The top screed, A, should be levelled 
from end to end and made parallel in depth with the 
crown moulding. Their levelness is tested with the aid 
of a "levelling" rule. The bottom screed, B, should 
be made parallel with the main cornice, so that the pro- 
jection of the vertical mouldings will be uniform. The 
vertical screeds, C, are next formed, making the first two 
near the internal angles, then two at the external angles. 
The intervening space is now set out, so that the screeds 
may be 8 to 10 feet apart. The screeds may be formed 
farther apart according to requirements. If there are 
vertical mouldings to be run in the cove, the screeds 
should be made at the sides of the proposed mouldings. 
It is always best to have two or three screeds near the 
angles, so as to give a bearing for the floating rule, R. 
This shows the position of the rule when floating the in- 
ternal angle. The external angles on the other side are 
formed in the same way. The distance between the 
screeds used for floating the angles can be regulated ac- 
cording to the depth or form of the angle. It will be 
understood that the floating rule must be sufficiently 
long to bear on two vertical screeds, and reach to the 
extreme point of the angle. The floating rule, R, here 
shown is termed a grooved floating rule. This is grooved 
on both sides, as shown by the section, S. 

Fig. 2 shows the elevation of a levelling rule as used 
for levelling dots for ceiling, beam, or crown screeds. 
This is similar to an ordinary parallel rule, but with the 
addition of a fillet, F, nailed flush with the bottom edge 



204 CEMENTS AND CONCRETES 

to form a ledge to carry the spirit level, L. The level- 
ling rule is applied on the dots to test if they are level ; 
this is proved by inspecting the spirit-level ; if one dot is 
too full it must be depressed until the levelling rule is 
level. 

Diminished Mouldings. — Mouldings that diminish in 
depth or projection as well as in width (termed ''double 
diminished mouldings ' ' ) are not so common as those that 
diminish in width only. The diminish in width is simple, 
and is obtained by the aid of a ''triple-slippered" run- 
ning mould and two running rules fixed to form a 
diminished space, as described hereafter. The formation 
of a regular and pleasing diminish in depth greatly de- 
pends on the profile of the moulding. A moulding hav- 
ing small members, especially at the sides, is more diffi- 
cult to diminish than one having large members, es- 
pecially one with plain and deep fillets at the sides. 
Three methods are here given for running double dimin- 
ished mouldings on domes, cupolas, or vaulted ceilings, 
or on lower surfaces. These methods give good results, 
especially if a little thought for the requirements of the 
case is bestowed on the designing of the moulding. 

Double Diminished Moiddings, False Screed Method — 
By this method the diminish in depth is obtained by false 
screeds, and the diminish in width by the aid of a dimin- 
ished rule, which is fixed on the centre of the profile or 
bed of enrichment. This method is elucidated in the fol- 
lowing illustrations. The annexed illustration No. 15, 
shows the section of a vertical moulding on the plaster 
or floated surface of the inside of a dome. C is the 
main cornice from which the inner line of the dome 
springs. The D's are dots which are used to regulate 
the -diminish of the false screeds. The various thickness- 
es and positions of the dots are obtained by setting oiit 



METHODS OF WORK 

the full size of the section on a floor or worked out to a 
scale. If the section is elliptical, dots should be placed 
at the points where the transition of curves takes place. 
When the surface of the dome has been floated^ the 
diminishing dots, D, are placed at each side of the in- 
tended moulding and at their prDper positions, begin- 




•Section 'Double Diminished Mouldings— 
False Screed Method. 

NO. 15. 

ning above the main cornice, C, and going upwards m 
rotation but having no dot at the top. The spaces be- 
tween the dots are next filled and ruled in, bearing on 
the various dots with the curved rules or templates. 
When ruling the top bay of the screed, the top enc' a" 
the rule bears on the original floating at the top or ex- 



2QQ 



CEMENTS AND CONCRETESi 




Plan. 



Elevation Double Dlmi- 
NisHED Mouldings — False Screed* 
Method. 

NO. 16. 



METHODS OF WORK 207 

treme point, this point being the true thickness of the 
screed. 

Illustration No. 16 shows the plan and elevation of the 
work. Fig. 1 shows it in progress, and Fig. 2 when 
finished. The A's on plan and elevation (Fig. 1) are 
false screeds, the B's are brackets, while C C indicates 
the diminished running rule. This rule is made as fol- 
lows: — First plane one face of a pine board about % 
inch thick, and of sufficient length and width for the 
desired purpose. On this make a centre line from end 
to end. From this centre line set off the width at one 
end, and the diminished width at the other end; then 
extend the diminished width lines from end to end, and 
then plane the running edges to the diminished lines. In 
order tO' allow the rule to bend freely to the curved 
surface, make a series of saw-cuts crossways on the back 
or bed face. The false screeds are made as already de- 
scribed. A centre screed for the running rule is made 
by the aid of a template. This is made with two slippers, 
one on each side, similar to a running mould, so as to run 
on the false screeds, the centre or cutting edge of the 
template being made to the depth of the proposed screed. 
The face surface of the bracket is then laid with gauged 
stuff and finished off by working the template up and 
down. This done, fix the diminished rule, C, on the 
centre of the screed. The running mould, E, on the 
plan is made with the slippers, one to bear on the centre 
screed and against the running rule, and the other to 
bear on the side false screed. The slippers are made 
circular on their running edges, so as to fit the circular 
screeds. A short slipper at the nib gives more freedom 
and ease when running the moulding, and the mould is 
not so liable to cut up the screeds. After the moulding 
is run on both sides, take the running rule off, then cut 



208 CEMENTS AND CONCRETES 

the false screeds down to the floating, and make the sides 
of the fillet good, and then fix the enrichment. Fig. 2 
shows the plan and elevation of the finished moulding 
and enricliment. A, on thie plan, shows one side of the 
moulding before the false screed is cut off, and G shows 
the screed cut off and the member made good to the 
floating. The amount of diminish from the bottom to 
the top of the moulding is shown at the brackets B ajid 
B, and by the profiles of the cornice on the plan and ele- 
vation. The bed and section of the enrichment is shown 
at F on the plan. As this enrichment is diminished (in 
width and projection) the whole length must be 
modelled. 

Running Double Diminished Mouldings, Diminished 
Rule Method.\ — This is a method which is introduced, 
and is somewhat similar to the first method described. It 
is well adapted for running mouldings, having no en- 
richment on the centre of the section, the bed of which 
may be used as a screed and bed for a running rule, as 
used for the first method. By this method the whole 
moulding is run in one operation. The diminish in 
depth is obtained by the use of two running rules 
diminished on the face, or in other words., diminished 
in thickness. The diminish in the thickness of the 
rules is obtained by setting the full size, as described for 
the false screeds in the first method. A series of saw- 
cuts must be made on the backs of the rules to allow them 
to bend to the circular surface of the dome. These 
rules act in a similar way to the false screed used in the 
first method, with the addition that they form the fillets 
of the outside members, thus avoiding cutting the screeds 
down and making good the fillets. They are also used for 
"obtaining the diminish in width. This is effected by 
first making a central line on the bed surface of the 



METHODS OF WORK 209 

proposed moulding ; tlien from this line, at each side, set 
out the half width of the moulding, including the bear- 
ing parts of the running mould. This is done at the 
widest or bottom end of the moulding, and at the nar- 
rowest or top end. Then from these width marks, lines 
are extended from end to end. On these lines, nails are 
inserted from 2 to 3 feet apart, which act as guides for 
fixing the running rules. The inner sides of the rule are 
placed against the outer sides of the nails and fixed, and 
then the guide nails are extracted, thus forming the 
diminished space and bearings. A triple-hinged mould 
with a slipper at each side is used, so that it will close up 
while being run up the diminished space. The stock is 
rebated, so that it will run on the tops and inner sides 
of the rules. The mould plate must be cut to fit the 
section at the greatest width of the moulding, but care 
must be taken that the depth at the outer members is 
the same as proposed for the top. The ends of the inner 
slippers and the adjoining parts of the stock are cut 
so as to leave an open space, to allow both parts to work 
freely when the mould assumes a raking position, as 
shown on illustration No. 17. 

The extra depth of the square of the outside members 
is formed by the running rules. It may here be re- 
marked that the thickness of the rules at the top should 
be made about % inch thicker than the depth of the 
square part of the outside members. For example, if 
the depth of the fillets or square part of the outside 
members is 1 inch, the rules should be II/2 inches thick 
at the top. This allows for the requisite bearing for the 
running mould. The ends of the stock that bear on the 
inside of the rules must be rounded off to allow the 
mould to run freely when it closes up while being ruu 
up between the diminished space. 



210 



CEMENTS AND CONCRETES 



The various parts of the running mould are shown in 
the annexed illustration No. 17. Fig. 1 shows the mould 





m/wmniiiuinujij Tm\inu]}i\uuuvum}wn//ninfnu///}Wf/ 



Elevations and Sfxtion of Running Mould 
AND Rules for Double jDniiNSHED Mouldings-* 
Diminished Rule Method. 

NO. 17. 

in position at the bottom cr widest part of the moulding ; 
R, R, are sections of the running rules; S, S, the slip- 



METHODS OF WORK 211 

pers; and H^ H, the hinges which connect the two 
halves of the stock to the slippers. The hinge which, 
connects the mould in the centre is fixed on the other 
side of the stock. Its position is indicated by dotted 
lines. Fig. 2 shows the form of the mould when at the 
top of the moulding. The letters correspond with those 
on Fig. 1. The thin seams at the centre and sides of the 
moulding which are caused by the joint of the mould in 
the centre and by the joint of the mould and the rules 
are cleaned off by hand. This method, like the first, has 
the defect that the actual diminish or the whole depth of 
diminish lies in the fillets cf the outside members of the 
moulding. The difference between the diminished mem- 
bers and the regular members will be most noticeable on 
the adjoining members, the vertical fillets of the cavettos. 
If this defect should prove offensive to the eye, it may to 
some extent be remedied by working these members down 
by hand, with the aid of planes, gouges, drags, and joint 
rules, after the moulding is run, so as to reduce the depth 
of the fillets, and throw the difference into the cavettos. 
A line should be set out to the desired diminish on the 
fillets to act as guides when working the cavettos down. 

Running Double Diminished Mouldings, Top Rule 
Method. — Running double diminished mouldings by the 
aid of a ' ' top rule ' ' is another method that I have intro- 
duced for this purpose. The diminish in width is ob- 
tained by fixing two slipper running rules to the de- 
sired diminish and a triple-hinged mould as previously 
described, and as shown at Figs. 1 and 2 on the an- 
nexed illustration. No. 18. Fig. 1 shows the running 
mould, M, and the slipper rules, R, R, at the full-sized 
or springing end of the moulding, and Fig. 2 shows the 
running mould and rules at the diminished end. The 
diminishing depth is obtained by the aid of a "top rule''' 



212 



CEMENTS AND CONCRETES 



which is fixed on two blocks, one at each end of the 
inoiildino", as shown at Fio'. 3. This shows the elevation 



'&? 



o 


; c 


o 


© 


o 


o 




Elevations, Plan, and Sections of 
•Running Mould and Rules for Diminished 
Mouldings— Top-Rule Method. 

NO. 18. 

oi one side of the running moulds at the springing and 
diminished ends of the moulding, also the running rules. 



METHODS OF WORK 213 

B is the section of the fixing block at the springing end 
of the moulding, and D is the fixing block at the dimin- 
ished end, upon which the top rule, T, is fixed. This 
rule is fixed on the slant, to suit the desired diminish. 
It must be made sufficiently wide to allow a bearing for 
a part of each half of the stock, M, M, of the running 
mould, and also fixed over the joints of the mould, as 
shown at T, Figs. 1, 2, and 3. The top rule being fixed 
on the slant, causes the running mould to gradually cant 
over when it is drawn from its upright position at the 
springing end of the moulding to the diminished end, 
as shown at Fig. 3, thus forming the diminish in the 
depth of the moulding. M a shows the end section of 
the stock in an upright position when at the springing 
end, and M is the section of the stock in a slanting posi- 
tion when at the diminished ends of the moulding. The 
dotted lines in both indicate the parts of the stocks in- 
side the slippers, and the angular dotted line at H, H, 
indicates the splayed or cut side of the hinge. S S is 
the outer elevation of one slipper when at each end of 
the moulding, and E is the slipper running rule. It 
will be seen that the running mould at Fig. 1 is some- 
what similar to the triple-hinged running moulds pre- 
viously described. But there are two important excep- 
tions, namely, the hinges at the centre and the two sides 
of the mould. 

The side hinges for this mould must be cut on one side 
and the angles rounded off, leaving only one screw-hole, 
so as to cause less friction, and allow this part of the 
hinge to turn on a screw when fixed on the slipper. The 
use of this will be seen hereafter. An elevation of a 
hinge, before and after it is cut, is shown at Fig. 4. The 
lower hole on the cut half of the hinge is used, because 
the nearer the ''turning points" or pivots are to the 



214 CEMENTS AND CONCRETES 

running ground or screed, as the case may be, the less 
will the bearing edges of the running mould rise when 
the mould cants over. For instance, if the "turning 
points" were made at the centre of the depth of the 
mould, the bearing edge of the mould would rise from 
the ground in proportion to the cant of the stock. This 
would increase the depth of the lower members (those 
below the pivots or turning points), instead of dimin- 
ishing them. This hole must be enlarged so as to admit 
of a short thick screw to give the necessary strength. It 
will be understood that this part of the hinge works on 
the plain part at the head of the screw. 

Having cut the right and left hinges, they are screwed 
on to the stock and the slippers of the running mould, 
keeping the half of the hinge with the three screw-holes 
on the stock, and the cut part with one screw-hole on 
the slippers, as shown at H, H, Fig. 1. It will also be 
noticed that these hinges are fixed at the lower edge of 
the mould. This is done so as to allow the stock of the 
mould to cant from its base for the reason already men- 
tioned. When scre^^dng the cut side of the plate to the 
slipper, allow just sufficient play for the hinge to turn 
smoothly but firm.ly on the screw. The centre hinge con- 
necting the halves of the stock, M, M, is formed with two 
pieces of metal plate. The inner ends are rounded off 
to allow them to turn and a circular orifice one-third the 
width of the plate is drilled at the circular ends, and 
then three or more screw-holes for fixing purposes are 
drilled on the ether ends. The two plates are fastened 
together with a flat metal ring or with stout copper wire. 
The thickness of this ring is regulated according to the 
size of the orifice, but allowing just sufficient play for 
the plates to turn both ways when the mould assumes a 
slanting and an angular position, as shown at Fig. 2. 



METHODS OF WORK 215 

An enlarged view of the centre hinge is shown at Fig. 5. 
The centre hinge is screwed on the inner side or profile 
of the stock, as shown at C, Fig. 1. An enlarged view 
of part of the stock at the joint, when inverted for fix- 
ing the centre hinge, is shown at Fig. 6. The top and 
bottom edges and the ends of the stock must be rounded 
off, to allow it to cant over easily. The diminish of this 
moulding, both in depth and width, as shown in the illus- 
tration, is a little more than may generally occur in prac- 
tice, but this is given to show the various parts more 
clearly, also what to avoid in the amount of diminish 
when using this method. 

The diminishing depth here shown is about two-fifths, 
and the diminishing width about one-third. The dimin- 
ishing depth, by this method, should not be overdone, 
because the running mould assumes an angular position 
both on plan and section, therefore it forms the vertical 
parts of the members in a slanting line and the horizon- 
tal parts out of a level. These defects become more pro- 
nounced at the diminished end of the moulding, as 
shown at Fig. 2. The top member can easily be made 
level and fair by hand, but . it would entail too much 
labor to rectify the defects of the other members, there- 
fore this method should only be used for small mould- 
ings or where the diminish in depth is of a slight nature. 
The seam at the top member, caused by the joint of the 
mould, is cleaned off and made good by hand. 

Cupola Panels and Mouldings. — In order to facilitate 
the setting out and formation of cupola panels and 
mouldings, the method of drawing them is given. This 
will be found very useful in the general setting out and 
construction of cupolas, whether in ''solid" or in 
"fibrous plaster." Various parts of cupolas and soffits 
of arches (from designs by J. Gibbs, architect, a pupil 



216 CEMENTS AND CONCRETES 

of Wren, and a great patron of the plasterer's art), with 
the method of drawing same, are illustrated on plate 11. 
To draw an octagonal cupola, as shown by the plan at 
Fig. 1, take A B (the width of one side of the octagon) 
as the base line. From the centre of this erect the per- 
pendicular line D C, then draw the lines C A and C B; 
this will give the triangle ABC, forming the plan of 
an eighth part of the cupola. The profile (Fig. 2) is 
made by the quadrant of circle (A B C) directly over 
the plan. Divide half the base line, A B on plan, into 
seven parts, as here figured, and six of them will make 
two panels ; the seventh will remain for the border. The 
same divisions must be marked on the profile over the 
line A B, as follows: — Take for the border at the bot- 
tom four parts, as shown in the plan ; place them on the 
profile from the base line to No. 1, and draw a line par- 
allel to the base line of the plan; measure the length of 
the two central lines marked 2 2, and place it in the 
profile for the second panel. From thence draw another 
parallel line, and measure the length of the two central 
lines at 3 3 in the plan to find the square height of the 
third panel, and so on to No. 8, as shown in the plan 
and profile. 

The elevation or upright side of this octagonal cupola 
(Fig. 3) is made by the following geometrical rule. 
First draw the base line (A B) on plan even with the 
base line (A B) of the profile; on this erect the perpen- 
dicular line (DC) for the centre of the side; then draw 
all the parallel lines as shown by G G, etc. Take half 
the length of each line, figured in the plan, and mark it 
on each side of the middle line of Fig. 3 until the length 
of every panel is fixed. From these lines and points the 
forms or outlines of the panels are taken. The inner 
divisions are brought over to the number of panels con- 




A. 



fi-^ 




Ssn-iNC our and. Plastering Cupola Panels and Mouldings, and Soffits of Arches. 

PLATE. U, 



METHODS OF WORK 217 

tained therein in the same manner as they appear in 
Fig. 3. The same rule is used for setting the side shown 
at Fig. 4. 

"With regards' to the soffits of arches, if they are 
divided into panels, they must be of any uneven number, 
as shown at K and L, by having a panel in the centre. 
The border must not be more than one-sixth nor less 
than one-seventh part of the whole breadth. The quad- 
rant or profile, E F (Fig. 2), on which the panels of this 
semi-circular soffit are divided, will be sufficient to ex- 
plain them. A circular soffit of lesser breadth is shown 
at M, and one of greater breadth is shown at N. Sec- 
tions of each soffit are shown at the top of the eleva- 
tions. 

The method of constructing the plaster work of cupo- 
las depends to some extent on the design and size of the 
panels and mouldings. For example, if the diagonal 
panels shown in Fig. 3 were sufficiently large to admit 
of a running mould to run a piece of moulding (on each 
side of the panels) net less in length than the mitres at 
each end, the best method would be to run the four sides 
of all the panels; but if the panels were too small to 
allow a running mould to run the requisite amount of 
moulding, it would be necessary to run a part, and cast, 
or run down, and plant the ether parts. In some designs 
it would be necessary to plant all the mouldings. In 
some cases the panel mouldings, from the base up to a 
third or fourth of the height of the cupola, can be con- 
veniently run; but the panels above this which become 
smaller, and are too small to admit of their being run 
with economy, should be planted. Another method is 
to run all the diagonal mouldings that spring from left 
to right, as from A to a, in one length from border to 



218 CEMENTS AND CONCRETES 

border, and then run the intermediate parts of the 
mouldings springing from right to left. 

The intermediate parts may also be run down, or cast, 
and then planted. By this method the intermediate 
parts only require mitring, and if they are planted the 
intersections only require to be stopped. If these parts 
are run, the brackets from right to left must be cut 
down at the intersections to allow the running mould to 
pass when running the mouldings from left to right in 
one length. Whichever method is employed, the surface 
must be floated true to the various curves to form a 
ground for the moulding's, whether run or slanted. The 
surface should also be floated sufficiently smooth to act 
as screeds without using gauged putty screeds for each 
moulding. This is done as described for panelled ceil- 
ings. The groundwork of the floating is effected by first 
forming a screed on the base border (A B), and one on 
the top border (at C), and then from these screeds as 
bearings, form tAvo screeds on the side or vertical bor- 
ders, thus completing the main screeds, and from which 
the panel surface is floated. Owing to the brackets and 
the form of the panels, it is a somewhat difficult opera- 
tion to float all the panel surfaces with a uniform depth 
and curve. It will be seen that a floating rule (cut or 
so constructed to clear the brackets), whether worked 
vertically or horizontally, cannot travel into the angles, 
and float the whole surface. This difficulty is overcome 
by making dots in each angle, or making narrow screeds 
from angle to angle of each panel. The horizontal dots 
or screeds, as the case may be, are ruled off with a gauge 
rule, which is cut to the required depth, and to bear on 
the side screeds. The vertical screeds are ruled off with 
the circular rule, on which pieces of board cut to the 
desired depth and length of the various panels have been 



METHODS OF WORK 219 

previously fixed. The intervening spaces are then ruled 
off with short rules cut to the angular curves. 

Another and better way is to cut an angular floating 
rule to fit the curve from A to a, and float all the panel 
surfaces in a line from border to border in one opera- 
tion. This angular rule is set out in a similar way as 
described for angle brackets. The rules for this or the 
first method must be made to suit the longest line or 
set of panels. After each set of corresponding panels 
in the other sides of the cupola is floated, they must be 
shortened to fit the next set of panels, and so on, until 
all the panels are floated. The mouldings being dimin- 
ished in width, are run from a diminished running rule 
fixed on a centre screed in the same way as described for 
diminished dome mouldings. The screed for this method 
is formed by an angular floating rule cut to the angular 
curve, as already mentioned. For some designs the 
moulding may be run with a t\\nn-slippered running- 
mould. This form of mould can also be used for form- 
ing about one inch of the panel surface. This acts as 
a ground for floating the panel surfaces. When large 
paterae are used, the ground panel surface may be cast 
with them, thus avoiding floating and setting. The oc- 
tagonal panels shown in Fig. 4 are formed in a similar 
way to Fig. 1. After the vertical and horizontal mould- 
ings are run, the diagonal sides of the octagons are 
planted. Where square panels form the design, the 
mouldings can be run with a radius-rod running mould 
from a centre pin and block. The sections of the soffits 
of the arches are run with a radius-rod running mould, 
fixed on a radius board, and the cross styles or mould- 
ings, as shown at K and L, are planted. A small portion 
of the arch should be run to form a ground on which the 



220 CEMENTS AND CONCRETES 

enrichments may be modelled. Fibrous plaster is well 
adapted for constructing the plaster lining of cupolas. 

Panelled Beams. — When panelled beams have mould- 
ings on the lower part of their sides or faces, and on the 
soffit to form a sunk panel, they may be run in two parts. 
Screeds are formed on the two sides, and one in the 
centre of the soffit. If the mouldings on the sides have 
more girth or are larger than the portion on the soffit, 
they may be run from rules fixed on the side of the beam, 
with the nib bearing on the style or on the soffits. If 
the style and mouldings on the soffit are small, the mould 
is made to run the face, style, and soffit moulding in one. 
If the styles are broad, the moulding on the sunk part 
of the soffit is run from a parallel running rule fixed in 
the centre of the soffit, thus forming a double rule to run 
each side of the sunk moulding. The latter way is most 
generally used. The end or other mouldings required 
for panelling the soffit are run down and planted. 

All beams of any length should always have a camber, 
not only to allow for any settlement that may take place, 
but to make it more pleasing to the eye. A beam dead 
level and straight has the appearance of sagging in the 
centre. This may be termed an optical illusion. 

Trammels for Ellipiical Mouldings. — It may at once 
be pointed out that an ellipse and an oval are not the 
same. Both ends of an ellipse are similar, and an oval 
is egg-shaped, one end having a greater curve than the 
other, therefore the term oval moulding or panel is 
scarcely correct when applied to the following illustra- 
tions. This term, however, is best known and generally 
used by most workmen in the building trades. The term 
''elliptical" is generally applied by plasterers when re- 
ferring to mouldings where the whole ellipse is not car- 
ried round, such as for mouldings or elliptical arches. 



METHODS OF WORK 



221 



windows, etc.; and the term *'oval,'' where the whole 
figure is completed, such as panels (elliptical on plan) 
formed on walls or ceilings. In consideration of the 
common usage of these terms, they will here be used in 
describing the setting out or v/orking of same. 

Trammels are often used for running oval panel 
mouldings, and for forming the lines when setting out 
oval templates. Trammels a,re made of wood or metal. 
A simple way to make a tram- 
mel for small work is to sink 
two grooves at right angles in 
a hardwood board (termed the 
plate), about 7 inches long, 
5 inches wide, and 1 inch 
thick. The grooves are about 
1-2 inch deep and 1-2 inch 
wide. Two hardwood pins are 
then made to fit the grooves. 
They have collars to bear on 
the surface of the plate. The 
upper part is made round to 
fit the centre holes of the rod. 
The subjoined illustration No. 
19 shows a template and 
various sorts of template pins. 
Fig. 1 is a view of a template, 
with the two pins, rod, with the 
running mould attached in 

position, and a part of a moulding. Fig. 2 shows various sec- 
tions of pins. A is the section of the pin as used in Fig. 1, 
and C is the plan of the pin at the intersection of the 
grooves. B is the section of a dovetailed pin used for 
another form of trammel. The rod is made to any de^- 
sired length, so that it may serve for various sized ovals. 





-tTrammels. 

NO. 19. 



222 CEMENTS AND CONCRETES 

The average size for this kind of trammel is about 1 foot 
6 inches long, 1 inch wide, and l-l inch thick. A series 
of holes 1-4 inch in diameter (to fit the head of the pin) 
is made about 1-8 inch apart on the flat side. The first 
hole is made near one end of the rod, and continued 
down the centre for about 15 inches^ leaving the blank 
space for screwing on to the running mould. A pin is 
now laid into each groove, and the size of the desired 
oval is obtained by regulating the length of the rod at 
each diameter by means of the holes. The pin in the 
short groove is the point from which the length of the 
oval is taken, and the pin in the long groove for the 
width. The trammel is fixed on the running board by 
means of two or more screws, as sho^vn. This size of 
trammel can only be used for oval mouldings from about 
10 inches to 36 inches at their longest diameter, there- 
fore larger sizes are required for larger ovals. 

A trammel for running large ovals (say from 6 to 10 
feet at the major diameter), if made solid, as shown in 
Fig. 1, would be too heavy and cumbersome for fixing 
on ceilings where the mouldings are run in situ. A 
lighter kind termed a "cross" template, is made as fol- 
lows : — Cut three flooring boards, one a little less in 
length than the longest diameter of the proposed oval, 
and two less than the short diameter. Lay them down 
on a floor in the forin of a cross (similar to the grooves 
in Fig. 1), and fix and brace them together. Four angu- 
lar braces will hold them together, and alloAv the whole 
to be fixed on the ceiling. On the centre of this ground 
make two lines at right angles to each other, and from 
these set out the width of the desired grooves at the ends 
and intersections, and then fix wood fillets, each about 
one inch thick and two inches wide, to the marks, thus 
forming the grooves. In order to prevent the pins drop- 



METHODS OF WORK 223 

ping out of the grooves when the trammel is fixed face 
downward on the ceiling, the inner sides of the fillets 
should be splayed so as to receive dovetailed pins, as 
shown at B, Fig. 2. This may also be effected by fixing 
running rules on the fillets so as to overlap about 1-4 
inch, over the groove space, thus forming rebated or 
square grooves. The pins are made with shoulders to 
fit the grooves: In both modes a 1-inch pin must be in- 
serted in the trammel pm to prevent the rod dropping. 

A strong, accurate, and permanent trammel can be 
constructed entirely with metal. To make this, procure 
a sufQcient length of metal tube, about 1-2 inch in diam- 
eter, having a slot about 1-8 inch wide, cut longitudi- 
nally. Cut the tube into four pieces, mitring the inter- 
sections, and fix and brace them together in the form of 
a cross, as already mentioned. A pin made to fit the slot, 
fixed in a ball made to fit the tube, completes one of the 
sliding pins. The rod may be made of metal or wood, 
but the latter gives more freedom for changing the size 
for different sized ovals. 

Various methods are employed for running oval panel 
mouldings on ceilings. The most useful are by means of 
trammels, or wood or plaster templates. A trammel is 
a good instrument for running oval panels where the 
mouldings are not wide. Wide mouldings (say over 1 
foot) cannot be run true or uniform in width in one 
operation with a trammel, because the running mould, 
which is fixed on the end of the rod of the trammel, 
assumes a raking position when it is between the right 
angle points of the major and minor diameters of the 
oval. This raking position takes place at the four joints 
or change of curves of the oval, and is more pronounced 
in extra wide mouldings. This difficulty is overcome by 
running the mouldings in two parts, using a trammel 



224 CEMENTS AND CONCRETES 

mould for running the first or inner part, and a rim- 
ning mould (horsed to run on the run part) for running 
the second or outer part. This is effected by dividing 
the section of the moulding into two parts, taking care 
to make the joint at the side of a fillet or in the center 
of a flat member at the outer side of the part to be run 
with the trammel mould, so as to allow for a good bear- 
ing (wide and strong) for the slipper of the running 
mould used for running the second part. The running 
mould for the first part is fixed on the rod of the tram- 
mel as already mentioned. The running mould for the 
second part is horsed with a circular slipper cut to fit 
the curve of the first moulding. If the oval has quick 
curves, a slipper with two pins will give the best re- 
sults. 

If there is an enrichment in or near the center of the 
moulding, run the moulding in three parts, using the 
bed of the enrichment (which is run wdth a trammel 
mould) diS a center running rule for running the outer 
and inner parts, which are run with circular or pin- 
slippered running moulds, as already described. It will 
be seen that by using either of these three methods, wide 
mouldings for oval panels can be run uniform on width ; 
the trammel mould giving the form of the oval to the 
fi.rst part of the moulding, or to the center running rule, 
and the curved slippered running moulds giving the de- 
sired uniformity of width to the full section of the 
moulding. Most forms of oval panel mouldings are best 
run with templates. When run with trammels, or with 
radius-rods, the running mould is apt to jump and cause 
cripples at the junction of the major and minor diam- 
eters. 

Templates for Running Elliptical Mouldings. — The 
true form of an ellipsis can only be derived from the 



METHODS OF WORK 



225 



diagonal cut from the cone or the cylinder, and the near- 
est approximation to this curve must be obtained by 
continuous motion. There is no other instrument so 
well adapted for effecting this purpose as a trammel. 
For a true ellipsis, make the distance from the outer end 
of the rod to the nearest point or centre pin equal to 




Template and Pin-Mould for Running 
Elliptical Arch Mouldings. 

NO. 20. 

half the shortest or minor diameter of the ellipsis, and 
from the centre pin to the outer pin equal to half the 
longest or major diameter. This shows the use of a 
trammel for setting out the lines to make a template for 
this form of ellipsis. 

The subjoined illustration No. 20 elucidates the method 
of setting out another form of ellipsis; also an oval hav- 



226 CEMENTS AND CONCHETES 

ing its major axis one-third greater than its minor. This 
also shows the template and a pin running mould in posi- 
tion for running an elliptical arch moulding. The 
template (Fig. 1) is made to extend below the springing 
line of the arch, so as to allow the mould to be run down 
to the spring of arch and save mitring. The template 
for running the arch extends to the shaded part; but 
to utilize the space the curve has been continued round 
to show a method of setting out a template from which 
an oval moulding can be run, the oval having its major 
axis one-third greater than its minor. The method of 
setting out is as follows: First draw the line AB, the 
greater diameter, to the desired length; then bisect it, 
and erect the perpendicular line CD ; this being the 
lesser diameter, is made a third less than the line AB. 
Then bisect each half of the line, which will divide the 
line AB into four equal parts and give the centres E, E, 
which are the centres for describing the ends, as from 
F to F, and Fl to F2. Then from the centres C and D 
describe the flat curves from F to Fl, and from F to F2, 
which complete the oval. It is, however, better to set 
out this template by the trammel, as the junction of the 
segments 'of the circles always has a more or less crip- 
pled look. 

Fig. 2 shows a "pin-mould" in position when run- 
ning an elliptical arch moulding. This mould is pro- 
vided with two hardwood pins inserted into the bearing 
face of the slipper. The pins bear on the edge of the 
template, and owing to their position, and being apart, 
allow the mould to take any change of curve without 
' ' jumping. ' ' 

Before running elliptical mouldings on arches or win- 
dows, the centres and running rods should be tested, so 
that the mouldings will intersect accurately, and so avoid 



METHODS OF WORK 227 

jumps at the change of curves. All centre pins should 
be level with each other, and equidistant from the centre 
of the arch or window. The outline and intersections of 
the proposed moulding can be tested by temporarily fix- 
ing a pencil on the outer and inner profiles of the run- 
ning mould, then working the mould over the screeds, 
so that the pencils will form two lines. I have heard of 
a three-centered elliptical hood moulding being run over 
a window with what is called a ' ' bolt radius-rod. ' ' This 
rod is made in two parts and connected with a hinge, 
and held straight when running the long diameter with 
a bolt and sockets where fixed at the joint. The run-' 
ning mould is fixed on one end, and a centre plate on 
the other in the usual way. The long diameter of the 
moulding is run first, and when the radius-rod reaches 
the change of curve the bolt is drawn back, and the short 
diameter of the moulding run with the short part of the 
radius-rod. A nail is inserted in a board which is pre- 
viously fixed in the window opening. The nail must be 
fixed in a line with the change of curve so as to stop 
the radius-rod, and hold the long part in position while 
the short part is working. The same operation is re- 
peated for the other side of the work. It is needless to 
say that this method is far too complicated to be serv- 
iceable for general purposes. 

Templates are used for running most forms of ellip- 
tical panel mouldings. Plasterers may make their own 
templates or running rules by using fibrous plaster casts 
as a substitute for wood. This is effected by first set- 
ting out a quarter of the proposed oval panel, then cut 
out or run a temporary plaster running rule to fit the 
inner line, allowing a space for the slipper of a running 
mould. Cut a reverse running mould to the section of 
the proposed fibrous plaster rules (say about 1 inch thick 



228 CEMENTS AND CONCRETES 

and 3 inches wide), then run the quarter length of the 
oval, and after making true joints at the ends, cast four 
fibrous plaster quarters, and then lay and fix them re- 
versely, thus completing the full oval template or run- 
ning rule. The full oval running rule can also be run 
in situ and in one operation. This may be done with 
a trammel or with radius-rods, according to the form 
and size of the panel. Strong and stiff gauged plaster 
or a strong white cement, should be used for the run- 
ning rule, to enable it to resist the friction of the run- 
ning mould while running the moulding. Radius-rods 
are more often used for setting out the lines for oval tem- 
plates than for running the mouldings. Circular mould- 
ings — vertical, horizontal, or angular — run off circular 
grounds require special running rules, so that they will 
take or bend to the double curvature. For this purpose, 
cane, flexible metal pipes, and wooden rules, having series 
of saw-cuts on the backs and sides, have been used, but 
cast fibrous plaster rules or a jack template are more 
suitable for most of these purposes. Template can also 
be made by means of a plasterer's oval. 

Plasterer's Oval. — The subjoined illustration (No. 21) 
elucidates the setting out of this form of oval to any 
given size, also the method of forming two oval mould- 
ings from two circle mouldings. The ovals are formed 
by running two circular mouldings in plaster, the diam- 
eter of one being exactly double that of the other. Each 
circle is cut into four quadrants or quarters. Two of the 
quadrants of the larger circle form the sides of one oval, 
and two quadrants of the smaller circle form the ends, 
the four segments making a fairly good oval. The re- 
maining segments constitute another oval of similar size 
and shape. The method is simple and speedy, and it 
can also be employed for th6 formation of elliptitjal 



METHODS OF WORK 



22e 




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55 



230 CEMENTS AND CONCRETES 

moulding's on arches, doors, or windows as well as for 
oval panel mouldings. The formation of ovals by this 
method has been employed by plasterers for genera- 
tions, but owing to the want of a definite rule for set- 
ting out this form of oval to any given size, its use has 
been somewhat limited. To meet this want, I have in- 
vented a method which can be adopted for most pur- 
poses, and which I give here for the first time. For 
want of a better name we have called this a "Plasterer's 
Oval, ' • for the reason that plaster lends itself more read- 
ily than any other material to the formation of circular 
mouldings. No one in the building trades can form a 
circle or an oval moulding so quickly and accurately as 
a plasterer. The method of setting out and of con- 
structing this form of oval is as follows : To set out an 
oval to a given size, the greater diameter being given. 
Take this greater diameter as a base to determine the 
required diameters of the large and small circle mould- 
ings, M and N, Fig. 2. Let the line A B, Fig. 1, be the 
given diameter, say 3 feet; on this form two squares, 
each according to their diameter would be 1 foot 6 inches 
by 1 foot 6 inches, as sho^m at C D E F and F H C ; 
then draw diagonals in each square as at C E and D F 
and C G and F H and at their intersections 1 and 1 as 
centres draw the circles 1 K and 1 K. The radius in this 
example would be 9 inches. The ciuadrants M and M 1 
correspond with the same letters in Figs. 2 and 3, and 
thev form the two ends of the oval. After this take C as 
a centre, and with a radius from C to at E or G de- 
scribe that part of the circle L from L 0, which forms 
the upper side of the oval; now take F as a centre, and 
with the same radius describe the lower side, joining K K 
at and 0, thus forming the plan of the oval as shown 
by the line ALB, and the dotted line below C. It will be 



METHODS OF WORK 231 

seen that the respective centres to describe this figure 
give the centres and diameters to run the two circle 
mouldings from which the ovals are formed. 

To construct the oval, first make a running mould to 
the desired profile, using a radius-rod in the usual man- 
ner, for running circles on the flat. Before running the 
mouldings, set out two lines at right angles on the mould- 
ing board, taking care to extend the lines a little be- 
yond the outline of the large circle, as shown by the 
dotted lines (Fig. 2). The extended parts of these lines 
act as guides for cutting the moulding into exact quad- 
rants. The intersection of them is the centre from 
which both circles are run. Apply the running mould, 
and turn it round, so that it leaves a faint mark on the 
running board to indicate the width of the moulding to 
be run. The width can also be marked by the aid of a 
pencil, holding it at the outside member, and turning the 
mould round, repeating this operation on the inside mem- 
ber. On this space drive in eight tacks, two in each 
quadrant, leaving the heads projecting about % inch. 
The object of these tacks is to prevent the moulding 
from lifting owing to plaster swelling, or from moving 
round while being run. Cover the tacks with clay to 
allow the moulding to be freely taken up after it is run 
and cut. The moulding is then run in the usual way, 
and is cut into four quarters, or quadrants. This is 
done by applying two set-squares, one inside and one 
outside of the moulding; and at one of the quarter lines 
lay a straight-edge over the moulding and against the 
set-squares. The moulding can then be marked or sawn 
at the proper place and angle. The dotted or quarter 
lines divide the mouldings into quadrants, and give the 
angles for cutting them. 



232 CEMENTS AND CONCRETES 

The use of extending the lines beyond the moulding 
will here be seen. A part may be obliterated while the 
moulding is being run, but the extended part will af- 
ford a correct guide for the outside set-square. If the 
quadrants are cut fine, square, and clean, the joints will 
be scarcely perceptible when the four segments are 
placed together. AVhen this circle is cut and taken off 
the board, the radius has to be altered to exactly one- 
half of the large circle, and the small circle is run and 
cut precisely in the same way as the large one. The four 
quadrants can now be fixed to form an oval, as shown 
in Fig. 3. If a quantity of oval mouldings be required, 
a casting mould can be taken oft' this oval in which they 
may be cast. It will be seen that the quadrants M and 
N 1 form the sides of the oval in Fig. 3, and the quad- 
rants M and M 1 form the ends. It will also be seen that 
after completing this oval there are four quadrants left 
to form another oval. If but one oval is required, run 
only one-half of each circle, allowing a little space 
beyond the centre line, so that a square and clean Joint 
can be cut. A thin saw with fine small teeth should be 
used for this purpose. 

Fig. 3 shows the four segments of the moulding in 
position forming the oval. In this figure the moulding 
is struck on the outside of the setting-out circle line, as 
shown in Fig. 1, but the moulding in Fig. 2 is struck on 
the inside of the setting-out lines. This is simply to 
show that the same centres can be used for moulding-s 
struck on either side of the lines. A mould for casting 
oval mouldings, also templates, can also be made by the 
above process. For this purpose a reverse running 
mould must be used for running the two circles. A 
plaster piece mould for casting oval mouldings that are 
undercut may also be formed by this method. In this 




Circular Mouldings on Circular Surfaces. 
Fio. I. — Elevation of SmaIl Cove, with Sections. 

FiC>^-3. — Section of Larce Cove, with Section and Elevation of Main Cornice. 

PLATK 111 



232 CEMENTS AND CONCRETES 



METHODS OF WORK 233 

case the running mould must be made and used as de- 
scribed for ' ' reverse moulds. ' ' 

Coved Ceilings. — Coves to ceilings are of various 
heights, a^ one-third, one-fourth, one-fifth, &c., of the 
whole height. The form of the cove is generally either 
a quadrant of a circle or of an ellipsis, taking its rise a 
little above the cornice, and finishing at the crown or 
other moulding. If the room is low in proportion to its 
width, the cove must likewise be low; and when it is 
high, the cove must likewise be so; by which means the 
excess of height will be rendered less perceptible. An 
example of two coved ceilings (from designs by James 
Gibbs) are shown is the annexed illustration No. 22. 
Fig. 1 shows the plan and elevation of a coved ceiling, 
with circular windows between the groins. Fig. 2 shows 
the plan and elevation of a coved ceiling, the design of 
which is less intricate than that of Fig. 1. The curve 
of this cove is a quadrant of a circle, as shown by the 
section at the side. The plans will enable the section 
of each design to be understood, and vice versa, and the 
whole will render the method of constructing coves and 
circular mouldings on circular surfaces (which is given 
hereafter) to be more clearly understood. The external 
and internal angle mouldings in these coves may be 
formed with a jack template or as described for coves. 

Circle Mouldings on Circular Surfaces. — The accom- 
panying illustration, Plate III, is given to elucidate 
various methods of running circular mouldings on cir- 
cular surfaces, shows the elevation of a cove suitable for 
an aquarium or marine hall. The external angle rib 
moulding, C, and the panel rib moulding, D, spring from 
the top or weathering of a main moulding, and intersect 
with a horizontal or crown moulding at the top of the 
cove. The section of the horizontal moulding is shown 



234 



CEMENTS AND CONCRETES 




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METHODS OF WORK 235 

at G, and the section of the panel moulding is shown 
above D; the section of the external rib being of course 
double that of the panel moulding. Where circular or 
straight mouldings intersect with each other, it is ad- 
vantageous in most cases to run the circular mouldings 
first, so that the whole of the moulding can be run, 
and leave the intersection to be mitred on the 
straight part, which is naturally the easiest part. In 
some examples it is not advisable to run the circular part 
first. For example, if the crown or horizontal moulding, 
as shown at 0, Fig. 1, was the lower part of a large 
croT\Ti moulding made to intersect with small cove 
mouldings, it would be best to run the straight moulding 
first, and then cut away as much of the straight mould- 
ing as will allow the nib of the running mould to pass 
while running the circular moulding. For the section 
in this example there would be very little mitring to do, 
as it would simply be a butt mitre up to the back of the 
circular mouldings. The external rib moulding, C, is 
best run v/ith a jack template. The circular panel 
mouldings (one-half of a moulding is shown at D) can 
be run by two methods. By the first, the 'moulding is 
run in three parts, using a sledge-slippered running 
mould fixed on a hinged radius-rod, and the two straight 
parts are run from running rules. By the second 
method, the whole moulding is run at one operation by 
using a fibrous plaster template, made as already de- 
scribed. 

Forming Niches. — Niches are recesses formed in walls, 
sometimes for the purpose of placing some ornamental 
object in them, such as statues, vases, &c., and they are 
often constructed in thick walls in order to save mate- 
rials. The plans or bases of niches are generally semi- 
circular, but some partake of all the segments under a 



236 CEMENTS AND CONCRETES 

semicircle, while others are elliptical, and in a few in- 
stances they are square or rectangular. The elevations 
of niches are generally in accordance with their plans, 
but variations from this rule are sometimes met with. 
The crown or heads of niches are generally plain, but 
they are sometimes enriched with scalloped shells, &c., 
or panelled with mouldings. With respect to the pro- 
portion of niches, there is no fixed rule, but the general 
one is twice and a half their width for their height. 
Various methods are employed in the formation of 
niches. The crowns of circular niches are generally run 
with a mould, because being circle on circle and small 
in surface, it is difficult to finish them true and smooth 
by hand. 

The accompanying illustration (No. 23) elucidates 
two methods of forming semicircular niches with the aid 
of running moulds. Fig. 1 shows the elevation, and Fig. 
2 the section of the crown and a part of the body of 
niche, with the centre-boards and moulds in position 
when forming the crown of the niche. Fig. 4 shows the 
section of the body of the cove, with the mould in posi- 
tion when forming same. By the first method the niche 
is formed in two operations, and by the second method 
it is formed in one operation only. For the first method, 
cut a running mould to the section of the niche, as shown 
at B, Fig. 1, then fix it on the centre board. A, with two 
hinges, keeping the upper surface or mould plate level 
with the top edge of the centre board, as shown on the 
section of the niche. Fig. 2. This also shows the end 
section of the centre-board and the mould, with the 
mould plate and a hinge. The dotted line indicates the 
distance the mould travels. After this, fix the com- 
bined centre-board and mould on the wall, tal?:ing care 
that the top edge af the centre-board is level and ex- 



METHODS OF WORK 



237 




Forming Niches with Running Moulds. 

NO. 23. 



288 CEMENTS AND CONCRETES 

actly at the ..•^ringing of the crown, C. The face of the 
wall must be floated plumb, and an allowance made by 
means of dots for the thickness of the setting coat be- 
fore the centre-board is fixed. After the crown is fin- 
ished, the centre-board and running mould is taken off 
the wall and separated. The mould is then horsed with 
two slippers to allow of its running the body or vertical 
part of the niche. The mould w^orfe on a running rule 
fixed on one of two screeds which are formed on the face 
of the wall, one on each side of the opening. Care must 
be taken that the screeds are plumb with the centre-board 
dots. Fig. 3 shows an elevation of the mould when 
horsed. B is the mould, D is a connecting board on 
which the mould is fixed by means of the cleats, C, C, 
and F, F, are the slippers. Fig. 4 shows an end section 
of the horsed mould in position when running the body 
of the niche. The base is finished by hand. 

By the second method the niche is run in one opera- 
tion, as already mentioned. This is effected by cutting 
a running mould to the vertical section of the niche, then 
fixing a pivot at the bottom and a bolt at the top. A 
w^ood block, v/ith a socket to fit the bolt on the mould, is 
let into the face of the wall at the top of the niche, and 
temporarity fixed, then another block with a socket to fit 
the pivot of the mould is fixed at the bottom of the 
niche. Care must be taken that the sockets are plumb 
and in a line w.'.th the centre of the niche, also that they 
are in a line with the face of the wall^ so as to allow 
the mould to form a true semicircle with perpendicular 
arrises. Place the pivot of the mould in the socket, and 
push the bolt up and secure it, and the mould is ready 
for woi"king. 

Fig. 5 shows a section of the niche with the mould in 
position. A is the mould with the pivot and bolt, and 



METHODS OF WORK 239 

B, B, are the socket blocks. A plan of the niche and 
mould is shown at Fig. 6. This also shows the plan of 
the pivot block, and a board which is sometimes used to 
secure the block. The dotted line indicates the dis- 
tance the mould travels. When there are splays or beads 
on the angle of the niche, the crown part is run with a 
radius-rod mould from a centre-board, and the vertical 
parts with a ''twin-slipper running mould" on running 
rules fixed on the wall screeds, or with a nib running 
mould on a slipper and a nib running rule. 

The vertical parts of the beads or splays may also be 
run with the mould shown in Fig. 3. For this purpose 
two plates cut to the desired section must be fixed on the 
mould, one at each side. The crown part is run with a 
radius-rod, as already mentioned. The crown surface 
and the angle moulding can also be run in one operation. 
This is effected by cutting a mould plate to the section of 
the moulding, including the section of the crown sur- 
face, then horsing it with a slipper to run on the wall 
surface, and a pivot to fit a socket formed in a centre- 
board, or with a radius-rod to work on a centre-board. 
A pivot will be found most suitable for small work and 
a radius-rod for large work. In either case they must 
be fixed on the centre of the mould, so as to be in a line 
with the mould plate. After the crown is run, the mould 
plate of the crown surface is cut off^ and the remaining 
part of the mould used for running the vertical mould- 
ings. 

In some designs a small moulding, such as an impost 
moulding, is carried round the body surface of the niche, 
and in a line with the springing of the crown. This 
moulding can be run in a similar way as shown at Fig. 
5, or by fixing a flexible wood or a plaster running rule 
on the body of the niche for the mould to run on. 



240 CEMENTS AND CONCRETES 

The crowns of niches that are parallel with small 
mouldings are best executed by making a model of the 
design, then moulding it and casting, and fixing as many 
as are required. In niche crowns that are enriched 
with shells, foliage, &c., the enrichment should be cast 
with the crown surface as a background. Fibrous plas- 
ter is well adapted for the construction of niches. For 
this purpose a reverse casting mould should be employed 
for forming the casts. This is made by cutting a re- 
verse running moidd to the section of the niche, and after 
a sufficient length of the body is run, cut the mould in 
half and run the crown. Then fix it on the end of the 
run body, and then fix rules at the sides and ends to 
form fences and rims, thus completing the casting 
mould. 

Any of the above methods for forming niches with 
running moulds can be advantageously used for forming 
the body and crown of the Ionic niche when such is re- 
quired. 

Running an Elliptical Moulding in Situ. 

In No. 24 a method of running an elliptical curve with 
a trammel is shown. Fig. 1 represents the front eleva- 
tion of the trammel mounted and in working order, and 
Fig. 2 is a section of the same. 

Take two floor boards, B, long enough to reach to the 
springing line of the arch, and nail them on the back of 
two lengths of 5 in. by 2 in.. A, which, as shown may be 
somewhat longer. Fix these up inside the jambs of the 
opening, taking care to see that they are perfectly up- 
right, and keep them the thickness of the trammel boards 
(which is 1 in.) back from the face of the opening on 
which the architrave is to be. Then cut three pieces of 



METHODS OF WORK 



241 



5 in. by 2 in., C, tight in between and secure them in 
place with 3 in. cut nails, taking care to see that the 
bottom side of the top one is above the springing line. 
Then prepare the trammel boards, D and E, 6 in. by 1 




PLASTEEEH S TRAMMEL f OE BtLIPIIGAL ARCHITfiAVE. 

NO. 24. 



in., and cut the slots, which are % in. wide and of a 
length which may be easily ascertained by simple geom- 
etry. Halve the boards together at the joint and fur- 
ther secure them by screwing a plate of the thickest sheet 
zinc obtainable on the back, as per Fig. 3. Nail the 



242 CEMENTS AND CONCRETES 

boards up as shown, keeping the horizontal slot central 
on the springing line and the vertical slot exactly in the 
centre of the opening, and be most particular to see that 
the whole lot is perfectly upright and level. Next pre- 
pare the tranmiel stick, 2 in. by 1 in., and mount the 
mould on the top in the usual manner, as shown. Then 
insert the pins in holes bored in the stick and secure by 
a screw through the edge. Have them just thick enough 
to work comfortably in the slots, and keep the centre of 
the pin XI, the distance of the rise, and the centre of 
the pin X2, the distance of the half span from the bot- 
tom member of the architrave. All the timber may be 
deal except the pins, which must be of some kind of hard 
wood. If well made and used with care this trammel 
ought to serve many times; the pins, of course, needing 
adjustment for arches of different size. 



MISCELLANEOUS MATTERS. 

Depeter. — This is a sort of a rough-cast^ and consists 
of forming a fair surface with coarse stuif or Portland 
cement. As soon as laid a hand-float is parred over the 
surface a few times to give it an even and uniform tex- 
ture, and wh'*^/^ it is soft, pressing in by hand, small 
pieces of hard coal, broken bottles, pottery, bricks, shells, 
stones, pebbles, or marble. The design may be varied and 
enriched by using various colored pieces in forming mar- 
gins, bands or other ornamentation. On the contrast of 
colors and the broad bands depends the effect of this 
class of work, A combination of "Depeter" and rough- 
cast may be used with excellent effect. 

Sgraffitto. — Sgraffitto or '''graffitto" is an Italian word, 
and means "scratched." Scratched decoration is the 
most ancient mode of surface decoration employed by 
man. The primitive savage of the flint-weapon period 
used this simple form of ornamentation. Scratched 
work, as used by prehistoric man, may be fitly termed 
the proem of the civilized arts of drawing, modelling and 
sculpture. The term is now employed for plaster deco- 
rations, scratched or incised upon plaster or cement be- 
fore it is set. It may be used for both external and 
internal decoration. The annexed illustrations (Nos. 25 
and 26) will demonstrate the high degree to which the 
art of sgraffitto attained in Italy, 

Some graffittos are really low relief work rather than 
the sgraffitto, they being very deep cut with the iron or 
steel point, which was necessitated by the final coat be- 
ing plastered on instead of washed on. Deep cutting 

243 



244 



CEMENTS AND CONCRETES 



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MISCELLANEOUS MATTERS 245 

gives a hard appearance to the design, prevents the water 
from running off the walls, and catches the dirt. In exe- 
cuting true sgraffitto, the cut or scratch should be ex- 
ceedingly slight — in fact, some parts scarcely percepti- 
ble. 

Sgraffitto decorations do not suffer materially from 
stubbing it with an old broom, leaving it barely half an 
inch from the finished face. For internal work, the ordi- 
nary pricking up suffices. When this is dry, a thin coat 
of selentic lime mixed with the desired coloring matter 
for the background, is floated over it. This background 
may be black, bone-black being used ; red, for which use 
Venetian or Indian red, or the ordinary purole brown 
of commerce, singly or mixed, to produce any tone de- 
sired; yellow, produced by ochres or umbers; blue, by 
German blue, Antwerp blue, or any of the commoner 
blues, avoiding cobalt, and these colors you may use to 
any degree of intensity or paleness. When this coat is 
nearly dry, skim over it a very thin coat of pure selentic 
lime, which dries of a parchment color and generally 
suffices. If you want a pure white lime, use a moderate 
quick-setting one, as stiff as you can work it, and as 
each variety of lime has its own individual perversity, I 
can give no general direction, and would advise the be- 
ginner to stick to selentic, which is always procurable. 
You have, of course, prepared your cartoon. This is 
pricked and pounced as for any other transfer process, 
and then with an old, well-worn, big-bladed knife, for 
there is no better tool, you can cut round all the out- 
lines, and with a flat spatula clear away all the thin 
upper coat, leaving the colored ground as smooth as you 
can. If your plaster is not quite dry enough for the 
two coats to separate easily, wait a little longer, but not 
too long, for that is fatal. By the time you have cleared 



246 CEMENTS AND CONCRETES 

out your background, the plaster will be in a good con- 
dition to allow you to cut out the finer parts of the de- 
sign, such as folds of the draperies, or the finer lines of 
the faces or of the ornament. Use your knife slightly 
on the slope, and if you want to produce half-tones, slope 
it very much; but, as a rule, the more you avoid half- 
tones, and the simpler and purer your line, the more 
effective your work will be. Eecollect, above all things, 
you are making a design and not a picture, and you 
must never hesitate, for to retouch is impossible. Some- 
times it may be desirable to gild the background, and 
you can then carve or impress it with any design you 
choose. It occasionally happens you want to give some 
semblance of pictorial character to your work when it is 
small in scale and near the eye, and then you can pro- 
ceed as though you were cutting a wood-block. 

By cutting out your ground color in places, and 
plastering it with that of another color, you may vary 
any portion of it you desire. You can also wash over 
certain parts of your upper coat with a water-color if 
you desire, combining fresco with the sgrafStto, both of 
which manners are often used ; but, as a rule, the broader 
your design, and the simpler your treatment of it, the 
better. It will be seen that this process is very available 
for simple architectonic effects; and for churches, hos- 
pitals, and other places where larg^ surfaces have to be 
covered, it is the least costly process that can be adopted. 
It has also the great advantage of being non-absorbent, 
and it can be washed down at any time. The artist is 
untrammelled by difficulties of execution, but he should 
bear in mind that the more carefully he draws his lines 
and the simpler he keeps his composition, the more 
charmed with the process he will be, and the better will 
be the effect of his work. 



MISCELLANEOUS MATTERS 247 

A well-known artist records his experience of sgraffitto 
as follows: 

''Rake and sweep out the mortar joints, then give the 
wall as much water as it will drink, or it will absorb 
the moisture from the coarse coat, as it will not set, but 
merely dry, in which case it will be worth little more 
than dry mud. Care should be taken that the cement 
and sand which compose the coarse coat should be prop- 
erly gauged, or there may be an unequal suction for the 
finishing coats. The surface of the coarse should be 
well roughened to give a good key, and it should stand 
some days to thoroughly set before laying the finishing 
coat. When sufficiently set, fix your cartoon in its des- 
tined position with nails; pounce through the pricked 
outline; remove the cartoon; replace the nails in the 
register holes; mark with chalk spaces for the different 
colors, as indicated by the pounce impression on the 
coarse coat; lay the several colors of the color coat ac- 
cording to the design as shown by the chalk outlines; 
take care that in doing so the register nails are not dis- 
placed ; roughen the face in order to make a good key for 
the final coat. When set, follow on with the final sur- 
face coat, only laying as much as can be cut and cleaned 
up in a day. When this is sufficiently steady, fix up the 
cartoon in its registered position; pounce through the 
pricked outline ; remove the cartoon, and cut out the de- 
sign in the surface coat before it sets; then if the regis- 
ter is correct, cut through to different colors, according 
to the design, and in the course of a few days the work 
should set as hard and as homogeneous as stone, and as 
damp-proof as the nature of things permit. 

*'When cleaning up the ground of color which may be 
exposed, care should be taken to obtain a similar quan- 
tity of surface all through the work, so as to get a broad 



248 CEMENTS AND CONCRETES 

effect of deliberate and calculated contrast between the 
trowelled surface of the final coat and the scraped sur- 
face of the simple contrasts of light against dark, or 
dark against light. The following are the proportions 
of the various coats: 

' ' Coarse coats : One of Portland cement to 3 of washed 
sharp coarse sand. 

''Color coat: One and one-half of air-slaked Port- 
land to 1 of color laid % inch thick. Distemper colors 
are Indian red, Turkey red, ochre, umber, lime blue; 
lime blue and ochre for green; oxide of manganese for 
black. In using lime blue, its violet hue may be over- 
come by adding a little ochre. It should be noted that 
it sets much quicker and harder than the other colors 
named. 

"Final coat, internal work: Parian, air-slaked for 
twenty-four hours to retard its setting, or fine lime and 
selenitic sifted through a fine sieve. 

"For external work: Three selenitic and 2 silver 
sand. 

"When finishing, space out the wall according to the 
scheme of decoration, and decide where to begin, and 
give the wall in such place as much v/ater as it will 
drink; then lay the color coat, and leave sufficient key 
for the final coat. Calculate how much surface of color 
coat it may be advisable to get on to the wall, as it is bet- 
ter to maintain throughout the work the same duration 
of time between the laying of the color coat and the fol- 
lowing on with the final surface coat; for this reason,, 
that if the color sets hard before laying the final coat, it 
is impossible to get up the color to its full strength wher- 
ever it may be revealed in the scratching of the decora- 
tion. When the color coat is quite firm, and all shine 
has passed away from its surface, follow on with the 



MISCELLANEOUS MATTERS 249 

final coat, but only lay as much as can be finished in one 
day. The final coat is trowelled up, and the design 
is incised or scratched out. Individual ta,ste and experi- 
ence must decide as to thickness of final coat, but if laid 
between % inch and 1-12 inch, and the lines cut with 
slanting edges, a side light gives emphasis to the fin- 
ished result, making the outlines tell alternately as they 
take the light or cast a shadow." 

Another mxethcd which I have used in sgraffitto for 
external decoration was done entirely with Portland 
cement. This material for strap-work or broad foliage, 
or where minuteness of detail is unnecessary, will be 
found suitable for many places and positions. Three 
colors may be used if required, such as black for the 
background, red for the middle coat, and grey or white 
for the final coat. These colors may be varied and sub- 
stituted for each other as desired, or as the design dic- 
tates. The Portland cement for floating can be made 
black by using black smithy ashes as an aggregate, and 
by gauging with black manganese if for a thin coat. The 
red is obtained by adding from 5 to 10 per cent, of red 
oxide, the white by gauging the cement with white mar- 
ble dust, or with whiting or lime, the grey being the nat- 
ural cclor of the cement. After the first coat is laid, 
it is keyed with a coarse broom. The second coat is laid 
fair and left moderately rough with a hand-float. The 
suction of the first coat will give sufficient firmness to 
allow the third coat to be laid on without disturbing the 
second. The third coat should be laid before the sec- 
ond is set hard. The second and third coats may be 
used neat, or gauged with fine sifted aggregate as re- 
quired. The finer the stuff, the easier and cleaner the 
work, and the cut lines are more accurate and free from 
jagged edges. The outlines of the design may be 



250 CEMENTS AND CONCRETES 

pounced or otherwise transferred to the surface of the 
work, and the details put in by hand. The thickness of 
the second ccat should be about 3-16 inch, and the third 
coat about % inch. The thickness of one or both coats 
may be varied to suit the design. The beauty of effect 
of this method of linear decoration, aided by two or 
three colors, depends greatly on the treatment of design, 
the clearness of the incised lines, and the pleasing color 
contrasts. It will be seen that in the three methods 
described there is a similarity, yet the method of using 
two color coats on a dark floating coat will give more 
variety and effect. There is a large use for sgraffitto in 
the future, as it has been in the past, and its use is inti- 
mately bound up with the future of cement concrete. 

In order that the foregoing examples of high-class 
sgraffitto may not deter the young plasterer from trying 
his " 'prentice han' " in this class of work, some simple 
designs are given in the annexed illustration (No. 27). 
Fig. 1 shows a design for a frieze in two colors. The 
ground may be black or red, and the ornament buff or 
grey. The colored material for the ornament is laid 
first, and the colored material for the ground laid last. 
Fig. 2 shows a design for a cove in two colors, one with 
two shades. The ground is grey, and the band work 
buff. A deeper shade of buff for the hone^^suckle can be 
obtained by brushing this part with liquid color made 
deeper than the original gauge, also by laying a black 
coat first, and in a line with the honeysuckle ; then laying 
the buff stuff for the band work next, and then laying 
the grey color last. In the latter case the honeysuckle 
is cut deeper than the band work, so as to expose the 
black coat. 

Different effects can be obtained by changing the col- 



MISCELLANEOUS MATTERS 



251 



ors. Sections of the surface of the frieze and part of the 
moulding are shown at the ends. 

Fresco. — The plasterer is closely allied to the artist 
painter. He has always to be in readiness to plaster the 
wall for the artist. Owing to the alliance with distin- 
guished artists, and the various methods of preparing 
and using the plaster materials, I am induced to give a 
few notes, also extracts from writers of authority. 




-Sgrafhtto Frieze in Two Colours. 
NO. 27. 



Fresco is a mode of painting with water-colors on freshly 
laid plaster while it remains naturally wet. It is called 
*' fresco" either because it was originally used on build- 
ings in the open air, or because it was done on fresh 
plaster. Fresco is an ancient art, being mentioned by 



252 CEMENTS AND CONCRETES 

Pliny. Mr. Flinders Petrie found some remarkably fine 
specimens on floors and walls at Tel-el-Amarna, which 
reveal the state of the art four thousand years ago. Fine 
frescoes were discovered in the ruins cf Pompeii. In 
one of the principal houses the plaster walls are adorned 
with theatrical scenes; in an inner room is the niche 
often to be seen in Pompeiian houses. The frescoes on 
the wall consist of floral dados. Above this is a whole 
aquarium, with shells, plants, birds and animals. They 
are all executed in their natural colors, and are natur- 
ally and gracefully drawn. Michael Angelo's beautiful 
fresco on the ceiling of the Sistine Chapel in the Vatican 
is grand both in conception and execution. It measures 
133 feet in length by 43 feet in width. Raphael's fres- 
coes in the Vatican, Farnesina Palace, &c., are wonder- 
fully fine, and may be regarded as the high-water mark 
of Cinque Cento decoration. 

For fresco or hiion fresco the lime has to be care- 
fully run, and the sand should be white, clean, and of 
even grain, being well washed and sifted to free it from 
impurities or saline properties. Silver sand is pre- 
ferred by some artists. The older the putty lime, the 
better the results. The lime is slaked in a tub, and then 
run through a fine wire sieve into a tank, and after being 
covered up, is left for three months. It is then put into 
the tub again, and re-slaked, or rather well worked, and 
run through a fine hair sieve into earthenware jars or 
slate tanks, and the water which collects at the top drawn 
or poured off, the jars or tank being covered over to ex- 
clude the air. Lime putty in this state will keep for an 
indefinite time without injury. From 2 to 4 parts of 
sand to 1 part putty is usual. Marble dust alone is 
sometimes used in place of sand, and also sand with 
equal parts. Every difference of lime and sand found 



MISCELLANEOUS MATTERS 253 

in various localities should be considered and tested be- 
fore using. A soft sand is quickly dissolved by a 
strong lime, and a plaster made of this is fit for use 
sooner, and will deteriorate more quickly than a plaster 
made with a less powerful lime and a harder sand, or 
with marble dust. 

The wall surface to be plastered must be well scraped 
and hacked, the joints raked out and brushed, and the 
whole surface well scrubbed and wetted. The rendering 
is done with the best possible prepared old coarse stuff. 
If the walls are rcugh or uneven, they should be first 
pricked up and then floated. In any case, the surface 
is left true, and with a rough face, to receive the fin- 
ishing coat. Portland cement or hydraulic lime gauged 
with sand, also gauged with coarse stuff, has been used 
where the walls were damp (damp is fatal to fresco), 
or if exposed to the atmosphere. When Portland cement 
or hydraulic lime is used, the work should be allowed to 
stand until thoroughly dry to allow any contained sol- 
uble saline efflorescence to come to the surface. This is 
brushed off with a dry brush, and a few days are allowed 
to elapse to see if there is a further efflorescence. When 
this is all extracted and swept off, and the artist is ready 
to commence, the wall is washed with a thin solution of 
the fine setting stuff, and then laid about % i^ch thick, 
with well-beaten, worked, and tempered fine setting 
stuff. It is then rubbed with a straight-edge and scoured 
with a hand-float (using lime water for scouring) until 
the surface is true and of uniform grain. Most artists 
prefer a scoured surface without being trowelled. No 
more surface should be covered than can be conven- 
iently painted in one day. While the plaster is still 
soft and damp, the cartoon iis laid on, and the lines and 
details pounced in or indented by means of a bone or 



254 CEMENTS AND CONCRETES 

hard-wood tool. Should the finishing coat get too dry 
in any part, it can be made fit for work by using a fine 
spray of water. The method of plastering and the gaug- 
ing of materials may slightly vary according to the de- 
sire of the painter and the kind of fresco in hand. The 
following is taken from an old manuscript dated 1699 : — 

''1. In painting the wall to make it endure the 
weather, you must grind colors with lime water, milk, or 
whey, mixed in size. 

''2. Then paste or plaster must be made or well- 
washed lime, mixed with powder of old rubbish stones. 
The lime must be often washed till finally all the salt is 
extracted, and all your work must be done in clear and 
dry weather. 

"3. To make the work endure, stick into the wall 
stumps of headed nails, about 5 or 6 inches asunder, and 
by this means you may preserve the plaster from peeling. 

"4:. Then with the paste plaster the walls a pretty 
thickness, letting it dry; but scratch the first coat with 
the point of your trowel longways and crosswaj^, as 
soon as you have done laying on what plaster or paste 
you think fit, that the next plastering you lay upon it 
may take good key, and not come off nor part from the 
first coat of plastering; and when the first coat is dry, 
plaster it over again with the thickness of half a barley- 
corn, Yery fine and smooth. Then, your colors being al- 
ready prepared, work this last plastering over with the 
said colors in what draught or design you please — his- 
tory, etc., I — so will your painting unite and join fast to 
the plaster, and dry together as a perfect compost. 

"Note — Your first coat of plaster or paste must be 
very haired with ox-hair in it, or else your work will 
crack quite through the second coat of plastering; and 
will spoil all your painting that you paint upon the sec- 



MISCELLANEOUS MATTERS 255 

ond coat of plastering; but in the second coat that is 
laid on of paste or plaster there must be no hair in it at 
all, but made thus: — 

Mix or temper up with well-washed lime, fine powder 
of old stones (called finishing stuff) and sharp grit sand, 
as much as you shall have occasion for, to plaster over 
your first coat, and plaster it all very smooth and even, 
that no roughness, hills, nor dales, be seen, nor scratch of 
your trowel. The best way is to float the second coat of 
plastering thus: — After you have laid it all over the 
first coat with your trowel as even and smooth as pos- 
sible, you can then take a float made of wood, very 
smooth, and 1 foot long and 7 or 8 inches wide, with a 
handle on the upper side of it to put your hand into 
to float your work withal, and thus will make your 
plastering to lie even; and lastly, with your trowel you 
may make the said plastering as smooth as possible. 

''5. In painting be nimble and free; let your work 
be bold and strong; but be sure to be exact, for there is 
no alteration after the first painting, and therefore 
heighten your paint enough at first; you may deepen at 
pleasure. 

^ ' 6. All earthy colors are best, as the ochres, Spanish 
brown, terra-vert, and the like. Mineral colors are 
naught. 

^'7. Lastly, let your pencil and brushes be long and 
soft, otherwise your work will not be smooth; let your 
colors be full, and flow freely from the pencil or brush; 
and let your design be perfect at first, for in this there 
is no alteration to be made." 

Fresco Secco. — Closely allied with the genuine fresco 
(fresco buono) is another kind called fresco secco (dry), 
or mezzo (half) fresco. The plaster work for fresco sec- 
co is similar to that used for fresco buono. It is allowed 



256 CEMENTS AND CONCRETES 

to stand until thoroughly dry. The surface is then 
rubbed '^ith pumice-stone, and about twelve hours before 
the painting is commenced it is thoroughly wetted with 
water mixed with a little lime. The surface is again 
moistened the next morning, and the painting begun in 
the usual wav. If the wall should become too drv. it is 
moistened with the aid of a syringe. There is no fear of 
joinings in the painting being observable, and the artist 
can quit or resume his work at pleasure. Joinings are 
distinctly noticeable in the frescos in the Loggia of the 
Vatican. Fresco secco paintings are hea^y and opaque, 
whereas real fresco is light and transparent. While the 
superiority of fresco buono over fresco secco for the 
highest class of decorative painting is uncpiestionable, 
still the latter is suitable for many places and forms of 
decorative paintings. The head by Giotto in the National 
Gallery, from the Brancacci Chapel of the Carmine at 
Florence, is in fresco secco. 

Indian Fresco and Marble Plaster. — "Fresco painting 
is a common mode of decoration in Jeypore, and is used 
in ornamenting walls inside and outside of buildings — 
also as a dado or border round the wainscot or on the 
floor — and on any surface where decoration is desired. 
The beautiful marble plaster on Avhich it is done is com- 
mon Rajputana. and is used to line the surface of walls 
or floors, and of baths or bath-rooms. It is admirably 
adapted to places where coolness and cleanliness are de- 
sired, and is very suitable to a warm climate. It would 
no doubt be more commonly used if pure lime could be 
obtained. 

"To prepare the marble plaster, the pracess in use in 
Jeypore is as follows: — Take pure stone lime, mix 
it with water until it has dissolved, then strain it through 
a fine cloth. In Jeypore the lime is made from pounded 



MISCELLANEOUS MATTERS 257 

marble chips or almost pure limestone. The substance 
which remains in the cloth is called bujra, and all that 
parses through the cloth is called ghole. These should 
be prepared a few days before they are required so as 
to allow time to settle, and every day the water should 
be changed, so as to leave a very fine sediment. 

''Jinki, which is also used, is pure marble ground to 
a very fine powder; kurra is a mixture of bujra and 
jinki; and jinkera is a mixture of ghole and kurra. 
These are the materials used, and the names by which 
they are known in Jeypore. In Madras, where similar 
plaster is used, it is made, I believe, from shells and the 
ingredients are probably known by other local names. 

'^If the surface to be polished is a slab or stone, the 
kurra mixture consists of 1 part by weight of burja and 
11/2 parts of jinki. If the surface is a wall or a chunam 
floor, it must be first thoroughly dry and consolidated — 
then take equal parts of burja and jinki to form the 
kurra mixture. Mix the burja and the jinki well to- 
gether; add a little water and grind them well together, 
in the same ways as natives mix their condiments, by 
hand with a stone rolling-pin on a slab, until they form 
a perfectly fine paste. Wet the surface which is to be 
I)olished, and spread over it a layer of this kurra mix- 
ture, about % inch thick. Then beat the surface gently 
with a flat wooden beater, sprinkling a few drops of 
clean water on the surface occasionally. Then mix a 
little ghole with the kurra plaster (described above as 
jinkera) and lay it on evenly with a brush as if it were 
a coat of paint ; rub the surface over carefully with any 
close-grained flat stone, called in Jeypore jhaon. The ob- 
ject of this is to smooth down all irregularity and 
roughness, and to prepare a smooth even surface. 
Sprinkle a few drops of water and repeat the process, 



258 CEMENTS AND CONCRETES 

taJiing care that no hollow places are allowed to re- 
raain. Paint it over with fine jinkera (ghole and 
kurra mixed), increasing the proportion of ghole, and 
rub it down well with a flat stone (jhaon) as before; 
then paint it over ^vith ghole only, after each coat rub- 
bing it do^vn carefully with the jhaon stone. After this, 
rub it all over with a soft linen cloth, called in Jeypore 
nainsukh, folded into a pad. Then give it another coat 
of ghole, and now rub it doAvn carefully with a piece of 
polished agate, called in Jeypore ghinti, until it begins 
to shine. The surface must not be allowed to dry too 
rapidly, or a good polish will not be obtained. Care 
must be taken that the lime has been thoroughly slaked 
in the first instance, or it may blister; also that the sur- 
face, if a floor, is thoroughly consolidated^ as the least 
settlement naturally causes the plaster to crack. The 
polishing process with the agate cannot be repeated too 
often; the more it is carefully done, the better will be 
the polish. Every time the agate is moved backwards 
it should be made to pass over a portion of its previous 
course, so as to prevent any mark or line at the edge. 
Lastly, if the surface is to remain white, take some water 
which has been mixed wdth grated cocoanut, and lay it 
on the surface. Let it dry, and then rub it down with a 
fixie cloth folded into a pad. If any coloring is desired, 
the same process is adopted until the polishing with the 
agate is begun. This is only done slightly. If any pat- 
tern is desired, it is drawn on paper and pricked out. 
The paper is placed on the surface, and is dusted with 
very finely powdered charcoal tied up in a muslin bag. 
The charcoal passes through the perforations and marks 
the plaster surface. The paints are mixed with water, 
and are painted on by hand while the surface is still 
fresh and moist hence the term fresco. Where a large 



MISCELLANEOUS MATTERS 259 

surface has to be done, it is necessary to employ several 
men at the same time, in order that the surface might 
be all painted before it has time to dry ; or else the pat- 
tern must be so arranged that the connection of one 
day's work with the work of the next will not be amiss. 
Immediately after the surface has been painted the 
colors are beaten in with the back of a small trowel, in 
such a manner that the color is not rubbed or mixed 
with the color adjacent. As soon as it shows to the 
touch that the color has become incorporated with the 
plaster, the surface is painted over with water mixed 
with grated cocoanut, and is then polished down with 
the agate. 

'^The following colors can be used in process: — Lamp 
black; red lead; green (from a stone known as hara 
pathar) ; yellow (from a stone called pila pathar) ; 
brown or chocolate. A little glue is mixed with the two 
first colors, and gum only with the others. The colors 
used are mostly earths or minerals, as other will not 
stand the action of the lime. Vegetable pigments can- 
not be used for this model of painting, even when mixed 
with mineral pigments, and of the latter only these are 
available which resist the chemical action of the lime. 
The lime in drying throws out a kind of crystal surface 
which protects the color and imparts a degree of clear- 
ness superior to that of any work in tempera or size 
paint. The process, although apparently simple, re- 
quires dexterity and certainty of hand, for the surface 
of the plaster is delicate, and the lime only imbibes a 
certain quantity of additional moisture in the form of 
liquid colors, after which it loses its crystallizing quality, 
and the surface or a portion of it becomes rotten. It is 
only after the lime has dried that such flaws are dis- 
covered, and the only remedy is to cut away the de- 



260 CEMENTS AND CONCRETES 

fective portion, lay on fresh plaster and do the work 
over again. The colors become lighter after the plaster 
dries, so allowance must be made for this. The advan- 
tages Avhich this process possesses are clearness, exhib- 
iting the colors in a pure and bright state; the surface 
is not dull and dry as in tempera or size painting, nor 
glossy as in oil painting; it can be easily seen from any 
point, and it is not injured by exposure to the air; it 
will stand washing, and can be cleansed with water with- 
out injury. 



J J 



SCAGLIOLA. 

Kistorical. — Scagliola derives its name from the use 
of a great number of small pieces or splinters; scagliole 
of marble being used in the best description of this 
work. It is said to have been invented in the early part 
of the sixteenth century by Guido Sassi, of Cari, in 
Lombardy, but it is more probable that he revived an 
old process, and introduced a greater variety of colors 
in the small pieces of marble and alabaster used to 
harden the surface, and better imitate real and rare 
marbles. It is sometimes called mischia from the many 
"mixtures of colors introduced by it. The use of colored 
plaster for imitating marbles was known to the ancients, 
although the pure white, or marmoratum opus and al- 
harum opus, mentioned by Pliny, was more used. The 
plastic materials used by the Eg;v^ptians in coating the 
walls of their tombs partook of the nature of marble. 
The ancients also used a marble-like plaster for lining the 
bottoms and sides of their aqueducts, which has endured 
for many centuries without spoiling or cracking. In the 
decoration of their domes the Moors used colored 
plasters, which have stood the ravages of time. The 



MISCELLANEOUS MATTERS 261 

beautiful chunam or plaster of India, as used by the 
natives, has a hard surface, takes a brilliant polish rival- 
ling that of real marble, and has withstood for many 
ages the sun and weather without sign of decay. The 
roofs and floors of many houses in Venice are coated with 
smooth and polished plaster, made at a later date, strong 
enough to resist the effects of wear and weather, 
without visible signs of crack or flaw, and without much 
injury from the foot. Scagliola was largely employed 
by the Florentines in some of their most elaborate works. 
It has been used in Prance with great success for archi- 
tectural embellishment. The rooms are so finished that 
no additional work in the shape of house-painting is 
required, the polish of the plaster and its evenness of 
tint rivalling porcelain. Scagliola is the material used. 
At times the surface of the plaster is fluted, or various 
designs are executed in intaglio upon it in the most 
beautiful manner. 

Scagliola is one of the most beautiful parts of decora- 
tive plaster work, and it is regrettable that there should 
not be a greater revival of such a charming and beautiful 
art. Its limited use in recent times is greatly owing to 
its manufacture being restricted by rules and rigid 
methods and even prejudices, and being confined to 
monopolists, who kept the method secret until it was 
looked upon as a mystery which greatly enhanced its 
cost. But through the information now at hand, com- 
bined with a little practical experience and enterprise, 
there is no valid reason why architects should not adopt 
it for second or even for third class buildings. It 
possesses great beauty, and is capable of affording grand 
effects and the richest embellishments in architecture. 
Scagliola, in skilful hands, can be produced in every 
variety of color and shade, in every possible pattern, in 



262 CEMENTS AND CONCRETES 

every conceivable form and size, from a paper weight 
to the superficial area of a large wall. It can be made 
at a price that would enable it to take the place of the 
most durable material now in use. Experience has 
proved that it will last as long as the house it adorns, 
and with an occasional cleaning, it will always retain its 
polish and beauty. It has been produced in past days 
in our own and other lands, and carried to such high ex- 
cellence, that many of the precious marbles, such as 
jasper, verd antique, porphyry, brocatello, giailo an- 
tique, Sienna, etc., have been imitated so minutely, and 
with an astonishing degree of perfection, as to defy de- 
tection. It will not only retain its polish for years, but 
can be renovated at much less comparative cost than 
painting and varnishing marbled wood, or plaster work. 
It is cheaper and more satisfactory to use scagliola in 
the first instance than to go to the expense of plastering 
walls, columns, etc., with Keen's or other kindred ce- 
ments, used for their hardness and ready reception of 
paint, which are to be afterwards marbled and var- 
nished. Both are imitations, but painted marble can 
never be compared with scagliola, which has the look, 
color, touch, and polish of the more costly natural 
marbles. 

Various Artificial Marhles. — Various patents have 
been taken out for the production of artificial marbles, 
having for their bases plaster of Paris. These patents 
will be briefly mentioned here. 

Evaux 's Artificial Marble is composed of plaster mixed 
with albumen and mineral colors, the ground being zino 
white. Rowbotham also employed plaster and albumen 
soaked in a solution of tannic acid. Lilienthal makes 
an artificial marble with Keen's cement, slaked lime, and 
curdled milk. 



MISCELLANEOUS MATTERS 263 

Pick's ^^Neoplaster." — This composition was patented 
in 1883, and is composed of 75 per cent, of plaster, mixed 
with feldspar, marl, coke dust, and pumice-stone. Gule- 
ton and Sandeman patented an artificial marble in 1876. 
It is composed of Keen's cement backed with libre, and 
soaked or brushed on the back with a solution of as- 
phalt. The slabs were made in glass moulds. La- 
roque's patent marble is formed of plaster and alum 
gauged with gum water, the veining being done with 
threads of silk dipped in the required colors. The 
backs of the slabs or panels are strengthened with can- 
vas. 

Mur Marble is composed of a mixture of Keen's and 
Marin's cement in equal proportions, made into a paste, 
with a solution of sulphate of iron and a small quanti- 
ty of nitric acid in water. The slabs are dried and 
tarred at a temperature of 250 degrees F. for about 
twenty hours, and when cool are rubbed, colored, var- 
nished, or japanned, as required. There is another 
patent formed of plaster, gauged with a solution con- 
taining tungstate of soda, tartaric acid, bicarbonate of 
soda, and tartarate of potash. Another is composed of 
Keen's cement 10 parts, ground glass 1 part, and alum 
% part, dissolved in hot water. 

Guattaris Marble is obtained by transforming gypsum 
(sulphate of lime) into carbonate of lime (marble). 
There are two methods. The first consists of dehy- 
drating blocks of gypsum, and then hardening by im- 
mersion in baths containing solutions of silicate of soda, 
silicate of lime, chloride of lime, sulphate of potash, 
soda, acid phosphate of lime, etc. The blocks are cut 
into slabs or carved before being put into the bath. The 
second method consists in dehydrating the gypsum, and 
bathing in some of the above chemicals. They are then 



264 CEMENTS AND CONCRETES 

dried and burnt at a red heat, and allowed to cool. 
After a second burning and cooling, the products are 
ground as for plaster. This powder is called ^'Marmo- 
rite". The marmorite is gauged in a trough with some of 
the water from the baths as above, kneaded into a paste, 
and the colors added and mixed. The paste is then put in- 
to moulds and pressed, and when set they are taken out, 
dried, and finally polished. Mineral colors are used. 
Yellow and its tints are obtained with citrate of iron 
dissolved in oxysulphate of iron, sulphate of cadmium, 
chloride of yttrium, chromate of lithium, and yellow of 
antimony. Red and its tints are obtained with dragon 's 
blood, sesquioxide of iron, mussaride red, and sulphate 
of didymium, and the salts derived from it, which give 
a rose color. Azure blue is obtained with sulphate of 
sodium mixed with acetate of copper and tartaric acid 
and oxide of cobalt. Green and its tints are obtained 
with verdigris, hydrochlorate of cobalt. Black is ob- 
tained by pyrolignite of iron reduced by boiling in gallic 
acid with sirco black. Black marble is also obtained 
by immersing gypsum blocks or slabs or the cast mar- 
morite in a hot preparation of bitumen. During this 
operation the dehydration of the material under treat- 
ment is accomplished, and the bitumen not only pene- 
trates the mass, but fills up all the pores and spaces 
evacuated by the water which was contained in the ma- 
terial treated, and a hard mass of brilliant black is ob- 
tained in every way equal to Flanders marble. It is 
said that the above imitation marbles are largely used in 
Florence. 

Scagliola Manufacture. — Scagliola can be made in situ 
or in the work shop, according to the requirements of the 
work; but in either case it is necessary that the work 
place should be kept at a warm temperature, and the 



MISCELLANEOUS MATTERS 265 

work protected from dust or damp atmosphere. The 
plaster should be the strongest and finest in quality, and 
free from saline impurities. It should be well sifted to 
free it from lumps or coarse grains, which otherwise 
would appear as small specks of white in the midst of 
the dark colors when the polishing is completed. Glue 
water should be made in small quantities, or as much as 
will suffice for the day, as it deteriorates if kept too long. 
Glue tends to harden the plaster, and gives gloss to the 
surface. Unfortunately it is also the cause of its sub- 
sequent dullness and decay when exposed to moisture 
and damp air, hence the necessity of using the best glue, 
good and fresh glue water. If scagliola is required to be 
done in situ on brick walls, the joints should be well 
raked out and the walls well wetted. This gives a good 
key, stops the excessive absorption, and partly prevents 
the evil effects of saline matters, that are found in most 
kinds of new bricks. These saline matters are the prin- 
cipal cause of subsequent efflorescence which sometimes 
appears on plastic surfaces, and is so unsightly and dis- 
astrous to surface decorations. Saline matters are also 
caused by acids, used in the manufacture of some ce- 
ments. Saline is also found in mortars made with sea 
water, or with unwashed sea sand. These impurities 
can be avoided by carefully selecting, mixing, and work- 
ing of the materials. Brick walls for scagliola should 
be allowed to stand as long as possible, and wetted at in- 
tervals. This allows more time for the saline to exude 
and be washed off. The exudation may be hastened or 
the salts absorbed and killed by brushing the walls with 
a solution of freshly slaked lime. This is allowed to stand 
until dry, and then cleaned off by scrubbing with warm 
water and a coarse broom. If space permits, a wall bat- 
tened and lathed is the best preventive. Scagliola slabs, 



266 CEMENTS AND CONCRETES 

screwed to plugs or battens, are protected from saline 
and internal damp. 

Iron columns to support overhead weights, and fixed 
as the building proceeds, are often covered with scagiio- 
la. If the work is done in situ, the iron core is sur- 
rounded with a wood skeleton and strong laths, or paint- 
ed wire lathing. The wood templates are cut, equal to 
the lower and upper diameters of the columns, and one 
fixed at the top and bottom of the shaft. The ground 
work is then ruled fair with a diminished floating rule. 
This gives a guide and equal thickness for the scag (the 
trade abbreviation for scagliola stuff). 

The floating coat is composed of the best and strong- 
est plaster procurable, and gauged as stiff as possible 
with sufficient strong size water, so that it will take from 
twelve to twenty-four hours to set. The floating is gen- 
erally brought out from the lath in one coat. A tenth 
part of well-washed hair is sometimes mixed with the 
gauged plaster, to give greater toughness and tenacity. 
The surface must be carefully scratched with a singly- 
pointed lath, to give a sound and regular key for the 
scag, which is laid on in slices, and pressed and beaten 
with a stiffish, square pointed gauging trowel, somewhat 
like a margin trowel. The scag- is laid about % inch 
fuller than the outline, and when set, the surface is 
worked down with a "toothed plane." This plan.e is 
similar to that used by cabinetmakers for veneering pur- 
poses. The irons are toothed in various degrees of fine- 
ness, and set at an angle of 70 degrees. If the columns 
are fluted, a half-pound plane is required for the flutes. 
As the planing proceeds, the outline is tested at inter- 
vals with a rule, as a mason does in using a straight- 
edge when working moulding*s. A planed or chisel-cut 
surface shows up the grain and figure of the marble 



MISCELLANEOUS MATTERS 267 

much better than if ruled. A rule is apt to work out or 
otherwise spoil the figure of most marbles. The t eating 
on the slices may disturb the figure of the marble at the 
outer surface, but if the scag is gauged stiff, the inner 
portion will be intact, hence the advantage of planing. 
To obtain greater cohesion between the scag and the 
floating, the latter is brushed with soft gauged stuff just 
before each piece of the former is laid. The scratching 
is also filled up at the same time, so as to obtain the full 
power of the key with the least amount of pressing on 
and beating the scag slices in position. When the shaft 
is planed, the wood colors are taken off; then the base 
and necking moulding, which has been previously cast, 
are screwed in position, using plaster (colored the same 
as the ground of the marble) for the joints. "When dry, 
the whole is stoned and polished. Pilasters or other 
surface work done in situ are executed by similar pro- 
cesses. Cast and turned work should always be support- 
ed by strong wooden frames, formed with ribs, and cov- 
ered with 14 inch to % inch thick sawn laths. The 
strength of the frames is regulated according to the posi- 
tion and purpose of the intended work. For example, a 
column with base placed on a square pedestal \'70uld not 
require so strong framing as the pedestal which has to 
support the column and base. Also being on the floor 
level, it is more exposed to contact and pressure. Fram- 
ing is also necessary for fixing purposes, and to allow 
for the work being handled freely when being moved 
from the work shop to the building, and when being 
fixed. Small work may be made without framing. 
Turned columns are framed in two different methods, 
each way being for a special purpose. If it is an "in- 
dependent column", or in other words a complete col- 
umn, not intended to surround a brick or iron core, the 



268 CEMENTS AND CONCRETES 

frame is made lifrhter and thinner, and in such wavs as 
to admit the cohimn to be cut either in two equal parts, 
or ^\dth one-third out, or just as much as will allow the 
larger part to pass over the iron core. Care must be 
taken that the inner diameter of the skeleton frame is 
greater than the diameter of the iron core. This is to 
allow for fixing. The outer diameter of the frame is made 
about 1 inch less than the finished outline of column, to 
allow % inch for the core and 14 iiich for the scag. The 
two parts of the frame are fixed with wooden pegs (not 
nails), so that they may be sawn when the column is cut 
into halves. This is not done until the column is pol- 
ished and ready for fixing. The parts are best separated 
by cutting with a thin and fine-toothed saw. The thin- 
ner the cut the better the joint. The two parts are 
fixed on the iron core with brass screws or clamps, from 
3 to 4 feet apart, and the joints made good with colored 
plaster as before. Sometimes a zigzag joint is made, the 
one side fitting the other, to give the marble or figure a 
more regular and natural appearance. The joints are 
then stopped with various tints, these being the same 
gauge as used for the face. 

Sometimes the framing is made longer than the shaft, 
so as to project at each end. These projecting parts are 
used as fixing points for screws, and binding round with 
hoop-iron before the plinth and cap are fixed. These 
parts project the edges of the work while being moved 
and fixed. Considerable skill and patience is required 
to make a strong joint, well polished, and imperceptible 
to the eye. The frames are made with solid ends, with 
a square hole in each to fit the spindle. The solid ends 
are cut out of inch deal, and are used to keep the skele- 
ton firm and in a central position when the spindle is 
turning on its bearings. One of the ends is fixed to 



MISCELLANEOUS MATTERS 269 

flange of the spindle with screws. If a case column is 
being made, the solid ends are taken off before the col- 
umn is cut ; but they form permanent parts of the fram- 
ing for an independent column. The mould is fixed at 
one side, and level with the centre of the spindle, which 
is the centre of the column's diameter. Care must be 
taken that the profile of the mould plate to the centre 
of the spindle is one-half of the required diameter at 
each end of the shaft. 

Vases are generally made without wood framing. They 
are turned on a spindle with a plaster core screwed to the 
flange in the form of a parabola, to give the form of the 
hollow inside. On the core a coat of scag is laid and al- 
lowed to set. This is scratched to give a key for the 
coarse plaster which forms the body of the vase. This 
is formed to the desired outer profile by means of a 
mould fixed on the outside, and muffled to allow for a 
thickness of outside scag. When the core is run, the 
muffle is taken off, and the scag laid, keeping it about % 
inch thicker than the true profile, to allow for turning 
and stoning. When the scag is set, it is turned, and 
then the vase is taken off the spindle and plaster core. 
The spindle hole is used as a key for a slate or iron dowel 
for fixing the vase on to the square plinth. The vase is 
then polished. Cheap work is usually run or turned 
with a mould. This is done to save turning with chisels, 
but it spoils the true figure of most marbles. 

A more recent way of imitating marbles is known by 
the name of Marezzo, which does not require so much 
polishing, being made on plate glass or other smooth 
surface. Keen's superfine plaster is used. The mode 
of making Marezzo is described later on. Specimens of 
the real marbles, to give the color and form of veining, 



270 CEMENTS AND CONCRETES 

spots, and figures, will be of great service to tlie be- 
ginner. 

Mixing. — Mixing the colors is an important part of 
scagiiola manufacture, and the following colors, mixing 
and mode of using, will serve as an index for the imi- 
tating of any other marble that is not detailed. Fine 
plaster (not cement) is used for making the best class 
of scagiiola, gauged with sized water, which is made by 
dissolving 1 lb. of best glue with 7 quarts of water. (This 
is known in the trade as "strong water".) The stuff, 
when gauged will take about six hours to set. All mix- 
ing is done on a clean marble or slate slab. One of the 
principal arts is the mixing, but there are no two men 
who mix exactly alike, and it is largely a matter of ex- 
perience. The chopping or cutting into slices with a 
knife is another important point in the mixing, apart 
of course from the special colors. Where there are two 
shades of one color in any given work, the cutting does 
not affect their original shade. No dry color is used, 
only ground water-colors. The beginner had better ex- 
periment with a small sample of "Penzatti" or Pen- 
zance marble. With one gill of size water, gauge plaster 
middling stiff, then mix thoroughly with the gauged 
plaster a little red. Do the same with a little black. 
(See quantities below.) Blend this stuff properly by 
working it on the bench with the hands (not tools), then 
.roll it out, and cut it into slices about one inch thick. 
Take up these slices, and part them with the fingers 
about the size of a walnut, and put them aside, a little 
distance apart, on a bench. 

The veining in this instance is white. Over these little 
lumps scatter half a handful of crumbs, made by re- 
serving a little of the gauged plaster, and making it 
crumbly with dry plaster, mixing with it a few small 



MISCELLANEOUS MATTERS 271 

bits of alabaster or marble. Then gauge a little plaster 
in a basin, with a tooth brush, about 2 inches wide, dip 
into this gauged plaster, and smudge the little lumps all 
over with it. Knock these lumps together into a big one, 
and chop the big lump three times. (This chopping 
means cutting with a knife into slices once, and knock- 
ing up again; cutting with a knife a second time, and 
knocking up again ; and then cutting with a knife a third 
time, when it is finished.) This lump is then ready to 
be cut into slices, and applied to any purpose required; 
but in this case, being wanted for a specimen, it is cut 
into slices about % inch thick, and laid close together 
flat on a sheet of paper, and allowed to remain until set. 
It is then planed, and when dry polished. This opera- 
tion is an embodiment of the principle of "scag" mix- 
ing nearly from beginning to end, only submitting one 
color for another for the various marbles. The mixing 
is generally known as plain and rich, and may be 
described thus: Take a Sienna pedestal, for instance. 
Two shades of sienna, plain mixing; one or two shades 
of dark with veining, rich mixing, both done on the same 
principle as Penzatti. They are cut into slices and laid 
on alternately. All veining of any color is done as 
described above, only modified by the consideration that 
if strong veining is wanted the stuff must be stifiish, and 
for fine veining it must be slightly softer. Various-sized 
measures for the water and scales for weighing the color 
should be used. Pats of each gauge should be set aside 
as test pats to determine when the main portion of stuff 
is set. It is advisable to number the pats for future 
reference as to quantity of colors, time of setting, and 
tints when dry. The various colors and tints are gauged 
and chopped as previously described, and according to 
the marble required. The core being laid on the skele- 



272 CEMENTS AND CONCRETES 

ton, and left in a keyed and rough state until dry and 
expansion ceased, it is ready when set for the scag. The 
core is now damped and well brushed with the white or 
other vein that has to be made. The veining is gauged 
thin, and being brushed and laid in the core, will tend to 
make the slices adhere better, and fill up the interstices 
caused by the jagged edges of the cut slices. The slices 
are then taken and pressed firmly onto the core, arrang- 
ing in proportion to the figure of the marble. To render 
the work more dense^ beat it with a flat-faced mallet 
and a large gauging trowel with a square end. Try the 
work with a rule to see if the surface is fair. The 
rough surface should not be less than Yq inch thicker 
than the true line of the work, to allow for planing and 
stoning. When required, pieces of alabaster are inserted 
before the stuff is set. Metallic ores are used in 
some marbles, also pieces of granite and real 
marble. When the scag is laid^ the work is left until 
set and dry. It is then planed stopped, stoned and 
polished. Columns and circular work are turned on a 
lathe, and the rough surface reduced to the true profile 
with long chisels similar to those for turning wood or 
other materials. This should not be attempted until the 
materials are thoroughly set. 

Colors and Quantities. — The following are the colors 
and quantities used for various marbles. The propor- 
tions of strong water, which is made varies, the due 
quantity should be tested by gauging small pats of 
plaster to ascertain the time of setting. As the tints of 
real marble vary in some species, the mixing must to 
some extent be left to the ingenuity of the workman. 
With a little practice and perseverance, a careful and 
observant man will soon succeed in getting the required 
tints. 



MISCELLANEOUS MATTERS 273 

Penzance Marble. — 10 oz. of light purple brown to 1 
pint. Veining (plain mixing), 2 oz. black to 1 gill; vein- 
ing (rich mixing) 5 oz. black to % pint; veining (rich 
mixing), 1 oz. black to I/2 gill. All liquid measurements 
refer to strong water. 

Egyptian Green. — 5 oz. black to 1 pint. Veining, i/^ oz. 
green to % pint light shade ; veining, i/4 oz. green to % 
gill. White the same, black chopped three times ; a few 
black spots same as brown Beige. 

Brown Beige. — Four shades — 1 light purple brown 
(indigo) ; 2 middle shades (blue black) ; 1 very dark 
shade (vegetable black). Veining, burnt sienna with red 
alabaster spots — 4 oz. (light shade) to % pint; 4 oz. 
(middle) to l^ pint; 4 oz. (very dark) to i/^ pint; 
% oz. burnt sienna to i/4 pint; i/4 oz. black to i/4 pint; 
% pint for the grey with crumbs, and red alabaster 
spots. 

Dark Porphyry. — Color, light purple brown, with 
black, and a little ultramarine, blue spots, black, ver- 
milion grey, and a little red. 

Green Genoa. — 2i/4 oz. green to I/2 pint (rich mix- 
ing) ; 5 oz. black to 1 pint. Veining, I/2 oz. green to i/4 
pint. White veining the same, with alabaster spots, and 
black. 

Rouge Royale. — Color, light purple brown, with a little 
sienna, and umber, with ultramarine, blue or blue black. 
Vert-Vert. — % oz. green to % pint; dark green with 
sienna; dry green plaster. 

Devonshire Bed Marhle. — All sienna work. Light 
mixing — 1 shade grey; 1 shade lemon chrome; 1 shade 
light purple brown; 1 shade flesh color; veining burnt 
sienna. Dark mixing.\ — 1 shade light purple brown, 
with indigo blue in it; 1 shade dark purple brown; 1 
shade middling purple brown; 1 shade grey; 1 shade 



274 CEMENTS AND CONCRETES 

lemon chrome. Yeining, burnt sienna, with small ala- 
baster spots. 

Sienna Mixing. — 5 oz. sienna to % pint, dark shade; 
3 oz. sienna to % pint, middle shade; 2 oz. sienna to 
% pint, light shade. 

Griotte Marble. — 10 oz. of light purple brown to 1 
pint 5 oz. of dark purple brown to % pint, with ala- 
baster spots. Ground with red veins, and small spots. 

Spanish Buff. — Burnt sienna, 2 shades, with large ala- 
baster spots. Veining, white and blue black, with small 
alabaster spots. Ground with red veins, and blue spots. 

Light Verd Antique.- — 2i/2 oz. green to l^ pint; 
1% oz. black to 1 gill ; i/2 gill black to 1 gill grey shade. 

Dark Verd Antique. — Green spots cut; grey spots cut ; 
black spots with green and grey. Veining 2% oz. green 
to ^2 pi^t (rich mixing) ; 2i/2 oz. dark green to % pint 
(rich mixing) ; i/4 oz. black to 1/2 pint (rich mixing). 

Plain mixing, same as above, with small alabaster 
spots, and small black spots. 

Black and Gold. — 5 oz. of black to 1 pint. Veining, 

2 shades dark sienna to % pint (rich mixing) ; 2 shades 
light to % pint (rich mixing) ; 2 parts light and grey, 
with alabaster spots, and crumbs. Veining must be stiff ; 

3 oz. of black to 1 gill. 

Walnut. — 2 parts burnt umber; 1 part rose pink. 

Yerta Alps Marble. — 5 oz. black to 1 pint. Veining, 
114 oz. of green to 1% gills ; i/4 oz. green to 1/2 gi^? with 
black crumbs chopped three times for the ground. 

Eosse De La Vantz Marble. — Rich mixing with indi- 
go blue — 1 shade light purple brown ; 1 shade dark pur- 
ple brown ; 1 shade Venetian red. Veining, black for " 
the ground, and white and green veining for the mixing, 
with alabaster spots and crumbs. 



MISCELLANEOUS MATTERS 275 

Polishing White Scagliola. — White scagliola is often 
made with superfine Keen's cement. A small portion of 
mineral green or ultramarine blue is added to improve 
and indurate the white color. White work requires spe- 
cial care to prevent discoloration or specks. When the 
work is left for drying purposes, or at the end of the day, 
it should be covered up with clean cotton cloths to pre- 
vent the ingress of dust, smoke or being touched with 
dirty hands. The tools should be bright and clean. Steel 
tools should be as sparingly used as possible. When the 
cement has thoroughly set and the work is hardj it is 
rubbed down with pumice-stone, or finely grained grit- 
stone, by the aid of a sponge and clean water, rubbing 
lightly and evenly until the surface is perfectly true. It 
is then stoned with snake-water (Water of Ayr), using 
the sponge freely and the water sparingly until all the 
scratches disappear. Afterwards well sponge the sur- 
face until free from glue and moisture. It is now ready 
for the first stopping. Stopping is an important part of 
the polishing process, and should be carefully and well 
done, to ensure a good, sound, and durable polish. 

First gauge a sufficient quantity of cement and clean 
water in a clean earthenware gauge-pot. The gauged 
stuff should be about the consistency of thick cream. It 
is well dubbed in, and brushed into and over the surface, 
taking care that no holes or blubs are left. When the 
stuff on the face gets a little stiff, scrape off the super- 
fluous stopping with a hard-wood scraper having a sharp 
edge. Then repeat the brushing (but not the dubbing) 
with the soft gauged stuff, and scraping two or three 
times, or until the surface is solid and sound. The work 
is now left until the cement is perfectly set. It is then 
stoned again for the third time with a piece of fine snake- 
stone, and stopped as before, with the exception that the 



276 CEMENTS AND CONCRETES 

superfine stopping is not scraped off, but wiped off with 
soft clean rags. The work is left until the cement is set 
and the surface dry. It is then polished with putty 
powder (oxide of tin), which is rubbed over the surface 
with soft clean white rags, damped with clean water. In 
polishing mouldings, the stone must be cut or filed to fit 
each separate member of the moulding. 

Polishing Scagliola. — The polishing of scagliola is 
slightly different. It is rubbed down with a soft seconds 
(marble grit) or gritty stone, using the sponge and water 
freely until the surface is true. The glut and glue are 
cleaned off with a brush and sponge, using plenty of 
water, until the pores are free from grit. The moisture 
is sponged off, and the work left until sufficiently dry. 
It is then stopped in the same manner as white work, but 
using stiff stopping for large holes and steel scrapers in- 
stead of wood. The stopping is made with the same 
kind of plaster, size water, and color as was used for 
the ground color of the marble that is being imitated. 
The stopping and stoning is repeated as before, and it is 
finally polished with putty powder, using pure linseed oil 
instead of water. The repeated operations of stopping 
and stoning must not be proceeded with until the 
previous stopping is perfectly set, and the work dry. A 
small portion of spirits of turpentine is sometimes added 
to the gauged colored stuff to facilitate the drying. The 
work between each combined stopping and stoning will 
take from one to five days to dry, according to the size 
and thickness of the work and the state of the atmos- 
phere. Never dry the work by heat. The thorough dry- 
ness and hardness of the work are most essential be- 
fore proceeding to polish with the putty powder and lin- 
seed oil, because any contained damp will work out and 
spoil the polish. Work not perfectly dry may take a 



MISCELLANEOUS IVIATTERS 277 

high polish, but it will soon go off when the damp comes 
through. Columns or large hollow work are not so liable 
to be affected by the damp, as it may escape through the 
back; but there must be some opening or ventilation to 
allow it to finally escape. 

If the polishing is well and carefully done, the polish 
produced on scaglioia will equal, if not surpass, that on 
real marble. Tripoli polishing stone, sometimes called 
alana, is a kind of chalk of a yellowish-grey color. Water 
of Ayr stone is also used for polishing. In large work 
a rubber of felt dipped in putty powder may be used. 
Salad oil is sometimes used for finishing. Linseed oil 
makes the hardest finish, and dries quicker. 

Marezzo. — Marezzo artificial marble manufactured 
from plaster or Keen's cement and mineral coloring mat- 
ter is made in wood or plaster moulds for moulded work, 
and on slate or glass benches if in slabs. If thick plate 
glass is used, the worker has the advantage of being able 
to look through it to see if the figure of the work re- 
quires altering. Glass also has the advantage of leaving 
a smoother and more polished face. All wood and 
plaster moulds should be got up with a good face, and 
properly seasoned, to save stoning and polishing the face 
of the work. Keen 's cement may be used advantageous- 
ly in making Marezzo, especially for chimney pieces, or 
other works required for exposed positions. Keen's 
cement for Marezzo should be of the highest class. If 
the cement is not of the best, it will effloresce, rendering 
the work of polishing difiicult, if not spoiling it alto- 
gether. Keen's cement requires no size water, but in 
gauging either Keen's or plaster, no more should be 
gauged than can be conveniently used. The quantities 
of colors, Keen's cement, plaster, and size water should 
be measured and gauged pats kept for future reference. 



278 CEMENTS AND CONCRETES 

All gauge-pots snould be of earthenware, a^ they are 
more easily cleaned out, and do not rust, as is the case 
with metal pots. All the tools should be kept bright and 
clean, as when working scagliola. 

Marezzo is made in the reverse way to scagliola, as the 
face or marble is put in the mould first, and the core or 
backing put on afterwards. 

All the mineral colors should be of good quality, in 
fine powder, and ground in water, known as ' ' pulp. ' ' A 
number of basins should be handy, and there should be 
a supply of twist silk in skeins varying in diameter from 
% to ^ of an inch, and cut into lengths of 14 to 18 
inches. For common work, good long flax fibre may be 
used. Canvas is also required. One end of the silk or 
fibre skein must be knotted. These are known as * ' drop 
threads. ' ' 

After the moulds are made, seasoned, and oiled, the 
young hand may begin by trying to make some easy 
marble, for a slab or chimney-piece. Gauge Keen's extra 
superfine cement or superfine plaster, in a large basin 
labelled No. 1, well mixing it until about the consistency 
of cream. This is pure white. Now pour a small quan- 
tity of this white plup into two small gauge-pots, Nos. 
3 and 4. Pour a third of what remains in the No. 1 
pot into another gauge pot, No. 2. Take some black- 
colored pulp, and make No. 1 a blackish-grey. Color 
in the same way No 2. only very much blacker than 
No. 1. No. 3 is now slightly tinted with pulp from No. 
1. This leaves No. 4 pure white. Then take a skein of 
twist (or threads), dip into No. 4, the pure white, and 
well charge it by stirring it about with the fingers ; take 
out the threads, taking each end. between the thumb and 
forefinger of each hand, and with the remaining fingers 
of each hand separate the threads, allowing plenty of 



MISCELLANEOUS MATTERS 279 



t{ 



swag", ' ' and strike this into the face of the mould, mak- 
ing each stroke at different angles, recharging the 
threads when necessary. Repeat this process with pulp 
from No. 3, but in a lesser quantity; then dip your 
finger ends into No. 2, and fling drops about the size of 
large peas all over the veining. These drops must be 
thrown on with considerable force, so as to cut into the 
veins as much as possible. Dip the fingers into No. 
1, and throw on No. 2, using alternately from each gauge- 
pot until you get a uniform thickness of surface (scag), 
about Yg inch in thickness. Now run a trowel over this 
to lay down any ridges. Cover the work with a piece 
of canvas, laying it evenly, smoothly, and without 
wrinkles. Be careful to put the canvas in the proper 
place, as moving it would spoil the lines of the veining; 
then spread a quantity of dry coarse Keen's lightly over 
the entire surface. This will absorb any superfluous 
moisture through the canvas. After the canvas and 
coarse Keen's have lain from ten to twenty minutes, or 
according to the stiffness of the gauge of the marble, the 
canvas and coarse cement/ are easily lifted off. Should 
any portion of the face of the scag leave the mould, and 
adhere to the canvas, it is taken off and put back in 
its place in the mould. The whole surface is now 
trowelled to render it dense and hard. The moisture 
should be sufficiently absorbed, or the trowelling may 
spoil the figure. The proper absorption of the moisture 
by the dry cement through the canvas, and well trowel- 
ling, are most essential to good work, ensuring hardness 
and density. 

The core or backing is now made by using the coarse 
Keen's previously used for absorbing the moisture from 
the face, gauging it with some fresh coarse Keen's as 
stiff as possible. This is laid on as thick as required. If 



280 CEMENTS AND CONCRETES 

the face of the scag be very dry, spread a thin coarse 
gauged Keen's, so as to give a perfect cohesion between 
the marble and the backing. The flat surface of the 
backing should always be ruled or floated straight with 
a uniform thickness, so as to give a true bed for the cast 
when it is taken out of the mould, and laid on a bench 
ready for stoning, stopping, and polishing. This can 
be done as soon as it is thoroughly set and hard, and in 
the same manner as scagliola. 

Marbles having long stringy veins require a different 
method of putting in the veins. Take the skeins, or 
* 'threads," by the knot with one hand, and thoroughly 
saturate them with the veining mixture, and run the 
finger and thumb of the other hand down the threads 
to clear them of any excess of veining color with which 
they may be charged. Then give the end not knotted to 
your partner, holding the knot in your left hand. Pull 
the threads asunder, so as to take the form of the veins 
of the marble you are copying, then lay them in the 
mould, leaving the knots hanging over the edge of the 
mould, or at least visible, to facilitate their removal 
when required. The threads should be arranged on the 
mould so as to take the form of the veining. The other 
colored materials are then thrown upon the thread veins, 
which quickly absorb the coloring matter from them; 
care being taken that the various colors are thrown or 
dropped from the finger tips, to form the figure of the 
body of the marble that is being copied. When the 
mould is sufficiently and properly covered with the 
marbling, take hold of the knots and withdraw the 
threads. These should be cleaned by passing down the 
finger and thumb for future use, saving the superfluous 
stuff for filling up any holes in the marbling. The 
absorption of the use of canvas and dry coarse Keen's, 



MISCELLANEOUS MATTERS 281 

and the filling in of the backing or core, is then 
proceeded with as before described. 

Granites, porphyries, etc., are made in a different 
manner. For porphyries with white and black specks, 
make a slab of white Keen's about % i^ch thick, and 
another in black, the same thickness. When they are 
set and hard, chop them into small pieces, then run them 
through a sieve, having a mesh to let through the pieces 
of the required size only. The pieces retained in the 
sieve can be broken and sieved again. The whole is 
now sieved again through a smaller mesh, which re- 
tains only the size wanted. The refuse can be used for 
small work or backing up. When the gauged stuff for 
the facing is mixed of the required tint (a reddish- 
brown), damp the black and white specks with the 
gauged color by means of a trowel and rolling, care 
being taken not to break the edges and faces of the 
black and white specks. When it is well mixed, lay it 
onto the face of the mould about 3-16 inch thick, press- 
ing it as firmly and evenly as possible. Then absorb the 
moisture by means of canvas and dry coai'se Keen's, 
trowel it well to give density, and fill in the backing or 
core as before. For "Rouge Royale," "Verd Antique," 
&c., requiring large white patches of irregular size, the 
sieving can be dispensed with. The white pieces are 
broken haphazard, and pieces of alabaster can also be 
inserted in these, and many other marbles, due regard 
being given to the size and quantity, so as not to produce 
an unnatural effect. The remainder of the figure is 
formed with the ''drop threads," and the other colors 
being thrown en. 

From this description of Marezzo, the workman will 
understand that in the case of marbles classed as ' ' Brec- 
cias,'* such as ''Roilge Royale," **Bla«k and Gold," &c., 



282 CEMENTS AND CONCRETES 

having patches and rough jagged veins in them, he must 
have flat pieces of the required color previously made 
and broken up, or alabaster, as the case may be inserted 
into them, and the veining done with the ' ' drop threads ' ' 
and that fine or long veining threads are not required; 
that unicolored marbles require no veining threads ; that 
the long veined marbles require the long threads, and in 
some cases the "drop threads" as well, and that granites, 
porphyries, &c., require no threads; that black is diffi- 
cult to make owing to the pure white cement requiring so 
much color; and finally, that in all cases, whether Ma^ 
rezzo or scagliola, the polishing is done in a similar man- 
ner, whether using plaster or Keen's cement. 

The details given must be carefully followed to pro- 
duce work artistic in figure and appearance. The direc- 
tions for making "St. Ann's" so far as manipulation is 
concerned, apply to all others. A little patience, prac- 
tice, and perseverance will soon give confidence and ex- 
pertness in producing sound scagliola and Marezzo. 

Granite Finish. — Granite is a peculiar finishing coat of 
plaster which is sometimes used in this country to imi- 
tate granite. For granite finish, first render the walls 
with hydraulic lime, and when nearly dry lay with a thin 
coat of the same material but colored light brown. Then 
while this coat is still moist, splash the surface lightly 
with white stuff, then with black stuff, using only half 
as much as used for the white stuff. The red stuff is 
best applied by dotting the surface with a small brush 
charged with the colored stuff. After these colored lime 
stuffs are firm, but not set, the surface is carefully trow- 
elled, using the minimum of water so as not to mix the 
various colored stuffs. The surface is sometimes left in a 
rough state, or as left when splashed. After the surface 



MISCELLANEOUS MATTERS 283 

is firm, it is set out and jointed to represent blocks of 
graite. 

Granite Plastering. — Granite plastering is a method, 
introduced by the author, to imitate granite. This mode 
of imitating granite is based on the scagliola process. It 
is also somewhat similar to the granite finish, and gives 
better and more reliable results. 

The method of executing granite plaster work is as 
follows : First select the most suitable lime or cement 
for the situation, such as Portland cement or hydraulic 
lime for exterior work, and Parian or other white cement 
for interior work. Having decided on the material, 
gauge three different colored batches, one white, one red, 
and one black, taking care that the stuff is gauged stiff 
and expeditiously so as to obtain a hard substance. The 
material is colored to the desired shades, as described 
for scagliola or colored stuccos. When gauged the stuffs 
are laid separately on a bench and rolled until about 
3-16 inch thick, and when nearly set they are cut into 
small irregular cubes and allowed to set and harden. The 
wall is then floated, ruled fair, and the surface keyed, 
and when set it is laid with a thin bedding coat of simi- 
lar stuff used for the floating, but colored light brown. 
The colored cubes are then mixed together in due propor- 
tions, and gauged with a portion of the light brown col- 
ored stuff and laid on the thin coat while it is soft. The 
whole is then firmly pressed with a hand-float until a 
close, compact, and straight surface is obtained, taking 
care when pressing the stuff not to break the cubes. 
After the stuff is set and perfectly dry and hard, the 
surface is rubbed down and polished, as described for 
scagliola or for marble plaster. The bedding coat should 
be sufficiently thick to receive the colored cubes, other- 
wise the larger cubes will project at parts, and cause 



284 CEMENTS AND CONXRETES 

extra labor in making a uniform and straight surface. 
Unles-s the cubes are fairly level when pressed, the sur- 
face will have a spotty appearance, besides being more 
difficult to polish. Where expense or time is a consid- 
eration, a striking appearance is obtained at less cost 
than polished work, by simply finishing the surface with 
a cross-grained hand-lioat. and a semi-polished surface is 
obtained by trowelling, or by scraping the surface with 
a joint-rule. Grey or light-colored granites are imitated 
by altering the coloi^ of the cubes and the bedding coat 
as desired. Bold and striking effects on wall surfaces 
can be obtained bv a combination of different colored 
granites, laid out in bands and bordei^. The effect can 
be increased by the introduction of bordei^ in sgraffito^ 
with the baiids in granite plaster. 



PART II 

CEMENTS AND CONCRETES, AND HOW TO USE 

THEM. 

It is not necessary to the workman that he should ex- 
pend a long period of his valuable time in reading up 
the history of cements and concretes, nevertheless it is 
proper he should be acquainted with the outlines of the 
origin, growth, and development of cements, concretes 
and their uses, and to this end the following brief his- 
torical summarj^ is presented, sufficient to give the work- 
man a fair idea of the beginning and growth of the use 
of cements and concretes : 

The word concrete is of Latin origin, and signifies a 
mass of materials bound or held together by a cementing 
matrix. The Romans used concrete B. C. 500. They 
made good use of lime concrete both in the construction 
of buildings and roadways. "Roads," says Gibbon, 
"were the most important element in the civilization 
of ancient Rome; and the cost of the Appian Way was 
such as to entitle it to the proud designation of ^Re- 
gina Yiarum' (the Queen of Roads)." The Appian 
(the oldest of the Roman highways) was commenced by 
Appius Claudius Caius, when he was censor, about three 
centuries before the birth of Christ. It extended from 
Rome to Capua, whence it was consequently carried on 
to Tarentum and Brundusium. Antonio Nibby, an 
archaeologist of the highest authority, states that the 
Appian Way had an admirable substructure, with lime 
concrete materials superimposed, and large hexagonal 

285 



286 CEMENTS AND CONCRETES 

blocks of stone laid on the top of all. The Romans built 
concrete aqueducts, often several miles long, to convey 
water to the cities. The palace of Sallust, the historian, 
was built about B. C. 50, and was frequently used as a 
residence by most of the emperors until as late as the 
fourth century. It was partly burnt by Alaric in the 
year 410. This once magnificent edifice was erected on 
a strange site, partly in the valley at the foot of the 
Quirinal Hill, and partly on the top of the hill. The 
latter portion of the palace, which was of great extent, 
has been almost wholly destroyed by the builders of the 
modern boulevard. The walls, which were thick and 
high, were most valuable examples of the Roman use of 
concrete, unfaced by brick or stone. There is still visi- 
ble evidence, in the form of impressions left on those 
walls, which clearly demonstrates their method of cast- 
ing walls in situ by means of wood framing. Rows of 
timber uprights, about 10 feet high, 6 inches wide, and 
3 inches thick, were fixed along both faces of the in- 
tended wall. Boards about 10 inches wide and 1% 
inches thick, in suitable lengths, were then nailed hori- 
zontally along the uprights, thus forming two parallel 
wooden walls, into which the concrete was laid and 
rammed until the space between the boards was filled 
to the top. "When the concrete had set, the wood fram- 
ing was removed, and refixed at the top of the concrete, 
the whole process being repeated until the wall was 
raised to the required height. This concrete was far 
more durable than brick or stone. The jerry-builders of 
the modern Rome had no difficulty in pulling down the 
stone wall of Servius, but the concrete walls required the 
use of dynamite to complete their destruction. After 
withstanding the wear and tear of many centuries, and 
the repeated onslaughts of the Goths and Yandals, it was 



HO W TO USE THEM 287 

left to the nineteenth-century speculative builder to de- 
stroy those interesting remains. 

The use of concrete for floors and roofs is of great an- 
tiquity. It was employed for this purpose by the Ro- 
mans in the time of Julius Caesar. Professor Middleton, 
in his first book, ' ' Ancient Rome, ' ' states that the whole 
of the upper floor of the Antrium Vesta is formed of a 
great slab of concrete^ 14 inches thick, and about 20 feet 
in span, merely supported by its edges on travertine cor- 
bels, and having no intermediate supports. In his sec- 
ond book, ''The Remains of Ancient Rome," Professor 
Middleton mentions that the Romans used concrete for 
the construction of the Pantheon, which was erected 
about the time of Christ. A curious and apparently un- 
accountable feature as regards practical purposes is that 
the concrete is faced with bricks, which were faced again 
either with stucco or (in special cases) with marble 
veneer. The Professor gives a sketch showing the ex- 
terior facing and the section of a wall of this kind, the 
entire mass being composed of concrete, except a facing 
of thin bricks, triangular in plan, with the points in- 
wards. As the author observes, these bricks could not 
possibly be intended as a matrix for concrete, as it would 
not have withstood the pressure of the latter while in a 
wet state. It must therefore have been necessary to re- 
tain the brick and the concrete with an external tim- 
ber framing, as in the case of unfaced concrete. There 
could be no gain of strength or other benefit to compen- 
sate for the time expended setting the brick skin. The 
dome of the Pantheon is 142 feet in diameter and 143 
feet high. This is also formed with brick- faced concrete. 
It has often been described and even drawn by various 
atithors as essentially a brick dome. Professor Middle- 
ton remarks there must have been very elaborate con- 



288 CEMENTS AND CONCRETES 

struction of centring for this and other massive concrete 
yanlts. He states they employed a method,, which has 
become common of late, to avoid the necessity of build- 
ing up the centring from the ground. They set back 
the springing of the arch from the face of the pier, so 
as to leave a ledge from which the centring was built, 
the line of the pier being afterwards carried up until it 
met the intrados of the arch, leaving it a segmental one. 
The Professor also found sigms of timber framing for 
walls in the remains of the Golden House of Nero, un- 
der the Thermae of Titus, where, he says, "the chan- 
nels formed by the upright posts are clearly ^^sible. 
These upright grooves on the face of the wall are about 
6 inches vdde by 4 inches deep, and they are afterwards 
filled up by the insertion of little rectangular bricks, so 
as to make a smooth unbroken surface for the plaster- 
ing. " This method is difficult to understand. Accord- 
ing to the present practice, the supports should be fixed 
outside the line of wall surface and leave no space to 
fill in afterwards. He also mentions a striking example 
of the tenacity of good concrete in the Thermae of Cara- 
calla, at a part where a brick-faced concrete wall origin- 
ally rested on a marble entablature supported by two 
granite columns. "In the sixteenth century," he says, 
"the columns and the marble architrave above them were 
removed for use in other buildings, and yet the wall 
above remains, hanging like a curtain from the concrete 
wall overhead. ' ' This proves that the Romans bestowed 
as much thought and care on the materials and their 
composition as they did on their construction. Profes- 
sor Middleton notes that the larger pieces of aggregate in 
the concrete, which are not close together, are so evenly 
spaced apart as to lead to the conclusion that they must 
have been put in by hand, piece by piece. 



HOW TO' USE THEM 289 

Dr. Le Plongeon, during his explorations in Peru, 
found many remains of mud concrete walls. Although, 
they were built many centuries ago, they have proved 
sufficiently durable to exist until to-day. The materials 
were placed between two rows of boards, and well beat- 
en, and the exteriors were sometimes decorated with plas- 
ter work. Thus it appears that the Peruvian builders of 
the period of the Incas anticipated by centuries the 
method (but not the material) of our modern concrete 
buildings. Le Plongeon 's researches conclusively estab- 
lish the fact that these Indians were masters of concrete 
building and plastering. The walls of the fortress of 
Ciudad Rodrigo in Spain are built of concrete. There 
are over twelve miles of arches and tunnels constructed 
with concrete in the Yarone Aqueduct, which supplies 
Paris with water. One of the arches over the Orleans 
Road, in the Forest of Fontainebleau, has a span of 125 
feet without a joint, the arches and the water-pipe or 
tunnel being entirely composed of beton, made with 
Portland cement, hydraulic lime, and the sand found on 
the spot. Concrete blocks weighing over 20 tons were 
used in the construction of the Suez Canal, 3,000,000 
tons of these blocks being required at Port Said alone. 
Besides the unquestionable durability of concrete, it also 
possesses fire-resisting and waterproof powers of the 
highest degree. Constructional works formed with con- 
crete carefully made and applied may be considered ab- 
solutely fire-resisting and damp proof; in fact, in these 
respects concrete has long since passed the experimental 
period, inasmuch as numerous tests, under the most try- 
ing and adverse circumstances, attest the superiority of 
this material for sanitary and durable work. 

The best concrete in France is that made under Coign- 
et's system of ''beton agglomere," and has been used 



290 CEMENTS AND CONCRETES 

with greac success in the construction of various large 
and important works. In Paris many miles of the sew- 
ers have been formed of this material, and a church in 
the Gothic style, from the foundations to the top of the 
steeple (which is 136 feet high) is entirely formed of 
beton. The work was prosecuted without cessation for 
two years, and was exposed to rain and frost, but has not 
suffered in the slightest way from the extremes of tem- 
perature. The strength of this material for constructive 
work may be judged by the thickness, or rather want of 
thickness, in the construction of a house, six stories high, 
having a Mansard roof — cellar, 19 inches, first story, 15 
inches; second story, 13 inches, and diminishing 1 inch 
every successive story, so that the sixth story was 9 
inches. The cellars have a middle wall from back to 
front, from which spring flat arches having a rise of one- 
tenth of the span, the crown being 5 inches thick, and 
at the springing 9 inches, which formed strong damp-, 
proof and fireproof cellars. There are many houses in 
Paris, and this country, constructed of this material. It 
has been used in London in the construction of sewers, 
&c. This concrete is composed of Portland cement, 
sand, and lime. Hydraulic lime is used for sewers and 
waterworks, and common lime for ordinary work. The 
lime is used in a powdered state. The whole of the ma- 
terials are mixed in a dry state by hand, and afterwards 
gauged in a specially made pug-mill. The least possible 
amount of water is added by means of a fine jet while the 
pug-mill is in motion. • The mixture is then spread in 
thin layers, and beaten by rammers formed of hardwood. 
The quantities for coarse work, where a fine face is not 
required, are : Portland cement, 1 part ; common lime, 
% part; gravel, 13 parts; coarse and fine sand, 6 parts. 
And for sewers : Portland cement, 1-5 part ; hydraulic. 



HOW TO USE THEM 291 

lime, 1 part; sand, 6 parts. And for external work of 
good quality: Portland cement, 1 part; lime, % part; 
sand, 7 parts. The above proportions are all by meas- 
ure. Specimens of Coignet beton at two years old have 
attained a crushing strength of 7,400 lbs. to the square 
inch. 

Fine Concrete. — "No book on plastering, " says Miller, 
"would be complete without a description of the meth- 
ods for working 'fine concrete' (here termed 'fine con- 
crete' to distinguish it from rough concrete as used for 
foundations, &c.), which is now coming into general use 
for paving purposes, staircases, and constructive and 
decorative works for buildings. Floors, roofs and simi- 
lar works which are finished with fine concrete, being 
within the plasterer's province, also demand description. 
The proper manipulation of the plastic materials, which 
is imperative for sound concrete, is undoubtedly plaster- 
er's work. The higher branches of concrete work, for 
architectural construction and decoration, embrace 
model-making, modelling, piece-molding and casting. 
Concrete construction is therefore essentially a part and 
parcel of the plasterer's art and craft. The construc- 
tion of concrete staircases in situ afi^ords a striking ex- 
ample of the necessity of employing plasterers. Only a 
plasterer can manipulate the materials correctly, make 
the nosing mitres sharp and true, and set the soffits of 
the stairs and landings, and form a true arris at the 
stringing, whereas the non-plasterer leaves the work un- 
even, rough and unsound. The non-plasterer can just 
manage to spread the stuff laid on the ground for him 
when laying paving, but he is entirely lost when the 
stuff has to be taken up on a hawk and laid with a 
trowel on an upright or overhead surface. He then gets 
upset, or rather he upsets the stuff. The non-plasterer 



292 CEMENTS AND CONCRETES 

possibly may have been an unfinished apprentice, or a 
dunce at his former trade, hence his trying another. 
These remarks are not caused by any hostility to other 
trades, but are inspired by the fact that many failures 
in the better class of concrete are due to the non-plaster- 
er's incapacity in working, and his lack of knowledge of 
the materials. Portland cement concrete pavements were 
first used about sixty years ago. Its introduction, im- 
provements, and subsequent rapid strides for paving, 
and in the construction of staircases, cast and made in 
situ, are due to the plasterers. Concrete is one of the 
best materials for paving the sidewalks of streets, abat- 
toirs, stables, breweries, &c. It is jointless, impervious, 
non-slippery, and can be laid with a plain surface or 
grooved to any desired form. The only objection to 
paving laid in situ for streets is that when it is cut to 
repair or alter gas or water pipes it is difficult to make 
it good without the patches showing. This slight defect 
can easily be overcome by cutting out the whole bay 
where the patches are, or by forming a movable slab 
over the pipes. 

There has been in recent years some controversy as 
to the department of the building trades to which lay- 
ing concrete paving properly belongs. The claim is un- 
doubtedly upheld in the strongest way for the plaster- 
ers. A further argument, if one is needed, to identify 
the operation as a plasterer's job, is that the tools, skill 
in which is necessary, are exclusively those of plaster- 
ers. The laying trowel and the hand-float are prin- 
cipally used; and none but plasterers exclusively employ 
them, no other workman in any branch of the building 
trades being habituated to their use. In every part of 
the world where <2oncrete paving has been used it has 



HOW TO USE THEM 293 

been laid down by plasterers, so that it may be looked 
upon as their legitimate sphere of work. 

Concrete is now extensively used in preference to 
earthenware for making sewer tubes. Experience has 
proved that the acids present in liquid sewage and the 
gases generated by the action of a faecal decomposition 
do not injure the concrete tubes, but on the contrary tend 
to harden them. Among the many unlikely purposes for 
which concrete has come into use may be mentioned stat- 
uary, vases, fountains, sinks, tanks, cisterns, cattle- 
troughs, silos, railway sleepers, platform copings, man- 
telpieces, chimney pots, tall chimneys, tombs, tombstones, 
and coffins. Concrete is slowly but surely coming to the 
front as one of the most useful, economical, constructive, 
and decorative materials for works requiring strength 
and endurance. It may now be said to be indispensable 
to the architect, engineer and builder. Concrete, when 
properly made with a Portland cement matrix, and slag 
or a similar aggregate, is undoubtedly the best fire-proof 
material used in any building construction. It can be 
made thoroughly waterproof and acid proof, and may be 
moulded or carved to any design and colored to any 
shade. After this brief historical review of concrete, the 
practical considerations of the modern working by plas- 
terers claim attention. Before describing the methods 
of working the concrete, a description of the materials, 
with their characteristics and application, is given as a 
preliminary guide and reference. 

Matrix. — Matrix is a word used to designate any ma- 
terial having a setting, binding, or cementing power, 
such as limes, plaster or cements. For concrete paving, 
stairs, floors, or cast work for external purposes, it may 
be truly said that there is only one matrix, namely, Port- 
land cement. 



294 CEMENTS AXD CONCRETES 

. Aggregate. — This is a term applied to those materials 
held or bound together by the matrix. Aggregates may 
be fibrous or non-fibrous, natural or artificial. The nat- 
ural aggregates comprise granite, stone, shells, marble, 
slate, gravel, sand, metal filings, &c.; the artificial slag, 
brick, pottery, scharfi", clinkers, coke-breeze, ashes, glass,- 
&c. ; and the fibrous slag, wool, coir, fibre, reeds, hair,- 
cork, tow, chopped hay, straw, shavings, &c. The fibrous' 
aggregates while being principally of a natural kind, are 
generally of a vegetable nature. They are commonly 
used with a plaster matrix for the interior works. The 
best aggregates for the upper coat of concrete paving 
are granite, slag, and some of the hard limestones. The 
best and cheapest for the first layer or rough coat are 
broken bricks, old gas retorts, clinkers, whin and other 
stones. Stone chippings from masons' yards and quar- 
ries are cheap and good. Shingles and gravel are also 
used, but owing to their round and smooth surfaces they 
afford little or no key for the matrix. When found in 
large quantities and at a cheap rate, they should be 
broken to render them more angular, so as to give a bet- 
ter key. Aggregates are broken by a crushing or stamp- 
ing machine. In Paris, the stone aggTegates used for 
casting figTires, vases and similar ornamental works is 
generally broken by hand. 

Aggregates should be clean, and their surfaces free 
from mud and dust. Coarse aggregates are easily 
cleaned by turning on a strong stream of water from the 
hose. The aggregates should be laid on an inclined plane 
to allow the water and dirt to run off. The importance 
of a clean aggregate is seen from the fact that briquettes 
made from washed particles resist a tensile strain from 
15 to 20 per cent, higher than those made from unwashed 
particles, when tested under similar conditions. 



HOW TO USE THEM 295 

Porous Aggregates. — All aggregates of a porous na- 
ture or having a great suction should be well wetted 
before being gauged, to prevent absorption of the water 
used for gauging the matrix. A porous aggregate re- 
quires more cement than one of closer texture, and is 
not as strong. Water has no power to harden or set an 
aggregate. It is used to render the mass plastic, and to 
set the cement. No more than is necessary for this pur- 
pose should be used. Sloppy cement will not attain the 
same degree of hardness as a firm or stiff gauged cement, 
consequently it stands to reason that if the water or a 
part of it be absorbed by a porous aggregate, it will ren- 
der the matrix, or that part next to the aggregate, friable 
and worthless. This may be proved by gauging a part 
of neat cement and spreading it on a brick and another 
part on a slate. It will be found that the latter will set 
and become hard, whilst the former will either crumble 
before setting, or partly set, without getting hard. All 
aggregates are more or less absorbent, but while the por- 
ous kinds will absorb the water from the matrix, not 
only leaving the portions in immediate contact with the 
aggregate inert, but also weakening the whole body of 
the concrete, the non-porous have little or no absorption, 
water being retained in the matrix, or a portion may lie 
on the surface of each particle of aggregate, thus tend- 
ing to harden the matrix and increase the general 
strength of the concrete. It may be thought that these 
defects are trivial, and can be overcome by thoroughly 
saturating the porous aggregate to prevent suction, but 
the fact still remains that after this or other excess water 
has dried out, the body of the concrete must still be por- 
ous, and this is one, if not the principal reason, why 
some concretes are not damp-proof. The quantity of 
matrix used for ordinary concrete being very much less 



296 CEMENTS AND CONCRETES . 

than the quantity of aggregate, and the matrix not being 
of sufficient thickness to resist the force of atmospheric 
moisture, the damp finds a ready passage through the 
porous portions. A mass of porous aggTcgate will ab- 
sorb external moisture, and this will gradually work 
through the body to the weakest or driest surface, or be 
retained for a time, according to the state of the atmos- 
phere. The extra keying power claimed for a porous 
aggregate is infinitesimal. It may be said not only to be 
of no value, but unnecessary, bearing in mind that in 
well-made concrete every particle of aggregate is envel- 
oped with matrix. 

Another point to be considered is the great tenacity of 
Portland cement to most clean surfaces, however smooth. 
Many men will have noticed how it ding's and adheres 
when set to iron, even to the smooth blades of trowels 
and shovels. The ultimate tenacity of neat Portland 
cement after being gauged twelve months is about 500 
lbs. per square inch. 

Compound Aggregates. — The proper selection and use 
of aggregates for a true concrete is not secondary, but 
of ec_[ual importance to the matrix. As inferior aggre- 
gates ai'e in the majority, it is advisable to take their de- 
fects into consideration. For concrete floors, roofs, and 
stairs, where strength, durability, and fire resisting prop- 
erites are imperative, gravel and coke-breeze as aggre- 
gates stand lowest in the scale. Owing to their abun- 
dance and cheapness, however, or for want of better ma- 
terials, their use is often unavoidable. Their individual 
defects may be partly if not wholly corrected by a com- 
bination of two or more aggregates so as to balance their 
respective good and bad qualities. It is self-evident that 
the hard, non-porous, and incombustible nature of gravel 
will correct the soft, porous, and combustible nature of 



HOW TO USE THEM 297 

coke-breeze, and that the light, rough, angular, and elas- 
tic nature and variety of size of coke-breeze will counter- 
balance the disadvantages of the heavy, smooth, round, 
and rigid nature and uniformity of size of gravel. The 
strength, irregularity of size, and form of broken bricks 
and its incombustible nature, causes it to be a direct gain 
to either of the above. The mixing of various aggre- 
gates may seem of small importance, but if by their judi- 
cious amalgamation the strength is enhanced, or the 
weight or cost of the material decreased, or gained, if the 
practice enables any waste or by-product to be utilized, 
then the advantage becomes obvious. To argue by 
analogy, it is well known that it is by the judicious com- 
bination and manipulation of various materials that 
mortars and cements attain their strength and hardness, 
therefore the same course will give equally good results 
with concretes, while rendering economy with safety pos- 
sible. 

The compressive and tensile strength of concrete is 
influenced both by the matrix and the aggregate. Aggre- 
gates which are uniform in size (or if of various sizes 
which are not graduated in proportion to each other), or 
having their surfaces spherical, soft or dirty, will not 
bind with the matrix, or key or bend with each other, so 
well as those which are of various graduating propor- 
tional sizes, and have their surfaces hard, angular and 
clean. 

Sand and Cement. — Sand is extensively used as an 
aggregate in Portland cement for cast work, mouldings, 
and wall plastering. Fine sand does not give so good 
results for strength as coarse sand, and a hard-grained 
sand is more durable than a soft one. Ground brick- 
bats or pottery, sandstone and flints, fine gravel, smithy 



298 CEMENTS AND CONCRETES 

ashes, and coke-breeze are often used as substitutes for 
sand. 

It has generally been assumed that sharp coarse sand 
is one of the best and strongest for gauging with cement, 
but, according to experiments made by Mr. Grant, clean 
sharp pit sand gives better results, as he found that 
whereas test briquettes having a sectional area of 2^/2 
superficial inches, composed of equal proportions of 
coarse sand, broke at the end of twelve months w^ith a 
tensile strain of 724 lbs., it required 815 lbs. to break 
briquettes composed of equal parts of cement and pit 
sand. With reference to various sands suitable for mak- 
ing mortar with cement, Mr. Grant's experiment is of a 
most surprising nature, as it indicates that sand made 
from ground clay ballast, or ground brick — which are 
identical — and Portland stone dust, were superior to pit 
or sea sand, or smiths' ashes. 

The following shows the results of tests of various 
aggregates made by Lieutenant Innes. The briquettes 
are composed of Portland cement, sand, or other aggre- 
gates, in the proportions of 1 to 2, and were kept in 
water for seven days. 

It will be seen that Portland stone dust gave the best 
results, and the others follow in this order — coarse sea 
sand, rough pit sand, smooth pit sand, drifted sea sand, 
and lastly smithy ashes. If the dust had been elimi- 
nated, the tests would be more valuable. The degree of 
coarseness has a considerable influence on the strength 
of the concrete and mortar. Fire sand makes weaker 
mortar than coarse. The following table gives the re- 
sults of two series of tests carried out by Mr. Grant. 
The cement was sifted through a sieve with 2,580 meshes 
to the square inch, and was made into briquettes with 2 



HOW TO USE THEM 



299 



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CEMENTS AND CONCRETES 



parts of sand by weight. All the briquettes are kept in 
water. 

Tensile Tests of Portland Cement and Sand (Coarse 

AND Fine). 



No. 




Sand 
tested 

by 
Sieves. 


At 28 
days. 


60 
days. 


91 
days. 


182 
days. 


273 
days. 


364 
days. 




First Series— 


Nos. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


lbs. 


1 


1 cement to 3 sand. 


20-30 


78.5 


113.9 


116.9 


142.3 


178. 


205.5 


2 


ditto. 
Second Series— 


10-20 


137.1 


239.5 


223. 


231.5 


254.5 


251.5 


8 


1 cement to 3 sand. 


20-30 


117.2 


134.5 


145. 


156. 


157.8 


213. 


4 


ditto. 


10-20 


212. 


236.5 


206. 


253. 


267.5 


273.5 



In the above each figure is the average of ten tests, 
the result being given in pounds per square inch. The 
sand used in tests 1 and 3 passed a sieve with 400 meshes 
to the square inch, and the sand used in the tests 2 and 
4, through a sieve with 100 meshes to the square inch. 

Fireproof Aggregates. — The selection of the best 
known fire-resisting aggregate for fire-proof concrete 
construction is of vital importance. Granite, stone, and 
flints splinter and crack when subjected to great heat, 
or to the sudden reaction caused by cold water used for 
extinguishing fires. Coke-breeze concrete, when under 
the influence of intense heat, as for example in the midst 
of a building on fire (stated by Captain Shaw to be 
from 2000 degrees to 3000 degrees Fahr.), will gradually 
calcine and crack, and finally fall to dust. 

Slag is one of the best fire-proof aggregates. It is a 
well-worn axiom that ''what has passed through the fire 



HOW TO USE THEM 301 

will stand the fire. ' ' There is no other material that has 
passed the ordeal of fire like slag. Its great hardness, 
density^ and angularity (when crushed) all tend to make 
it one of the best substances for fire-proof construction. 
Slag is cheap and abundant, but requires great care in 
selection, as some kinds contain a large amount of sul- 
phur, which is very detrimental to Portland cement, 
causing the concrete to blow and expand. The presence 
of sulphur can often be detected by the smell alone. 
When sulphur is present in a heap that has lain for 
some time, or sufficiently long to allow the atmosphere to 
cleanse the outer surface, it is more difficult to detect. A 
hole should then be dug in the heap, and the presence 
of sulphur can be ascertained by smell, heat, and color. 
It will smell strong, and if new will be warm, and show 
yellow patches. The power of the sulphur is so great 
that washing the slag once will not entirely cleanse it. 
In some cases frequent washings and long exposures to 
the air are necessary. There are some slags that are free 
or nearly so from sulphur, and which can be had direct 
from the iron furnaces. The slag from coal and iron 
furnaces is largely employed for concrete paving. It is 
hard and practically free from sulphur. The best size 
is % inch screenings. This when sifted yields a fine kind 
for topping, and the residue is useful for the rough coat. 
The next best fire-resisting aggregates are fine-briclis, 
pottery, scharff, hard clinkers, and pumice-stone. The 
last has the advantage of being extremely light, but it is 
too soft for the frictional wear. Coke-breeze may to a 
certain extent be deprived of its combustible nature and 
rendered more fire-resisting by washing and passing it 
^^hrougrh a i/4 iiich sieve, then adding 1 part flowers of 
sulphur and 10 parts fine broken bricks to 20 parts of 
«oke-breeze. The larger breeze rejected by the sieve can 



302 CEMENTS AND CONCRETES 

be broken small, or used for internal layers of concrete. 
The bricks should also be passed through a I/4 inch sieve. 
The finer the breeze and brick^ the better for recei\dng 
and retainino' nails. 

Void^ in Aggregates. — The quantity of voids or in- 
terstices depends on the shape and size of the aggTCgates. 
The least quantity of voids will be found in those aggre- 
gates which are broken small, and contain pieces of va- 
rious sizes. Gravel free from sand contains about 30 
per cent, of voids, and broken stone of uniform size about 
50 per cent. Sand is often mixed with gravelj stones, 
&c., to lessen the quantity, or fill the voids, so as to en- 
sure the full strength of the concrete, without adding 
more cement than the proper ratio. The following 
method is used to ascertain the voids in aggregates : — 
Fill a box of kno^Ti capacity with damp, broken aggre- 
gate ; start shaking it during the operation : then fill the 
box to the brim with water ; the quantity of water is the 
measure of the voids in the aggTegate. Having now 
briefly reviewed the characteristics of the aggregates 
most used, the practical conclusions to be drawn are that 
they should be angular in form, Iiard in nature, grad- 
uated in size, and clean. 

Crushing Strength of Concrete. — The crushing 
strength of concrete depends upon the ratio of cement, 
and the nature of the aggregate. Another important 
factor is compression, done by heating and ramming. 
Compression increases the weight of concrete about 4 per 
cent., and the strength about 25 per ceni.. The follow- 
ing table shows the crushing strength of concrete made 
with Portland cement and various kinds of aggregates as 
given by Mr. , Grant. The tests were made with 6-inch 
cubes. One-half were compressed by heating the con-e^ 
Crete into the mould with, a mallet; the other half wer^ 



HOW TO USE THEM 



303 



not compressed. The whole were kept in the air for a 
year before being crashed. 

The granite and slag might have been expected to 
have given the better results. It is probabl-e that they 
were unwashed^ and contained a considerable amount of 
dust. If the compression was done by hydraulic power, 
so as to obtain a uniform compression in all the cubes, 
the results would be more reliable. 

Crushing Strength (in Tons per Square Foot) of 
Portland Cement Concretes Having Various 

Aggregates. 





Six to One. 


Eight to One. 


Ten to One. 


Nature of Ag- 
gregate. 


Com- 
pressed. 


Not 
Com- 
pressed. 


Com- 
pressed. 


Not 
Com- 
pressed. 


Com- 
pressed. 


Not 
Com- 
pressed. 


Ballast 

Portland stone 

Granite 

Pottery 

Slag 

Flints 


81.6 
162.4 
122. 
115.2 

92. 

82. 


72.8 
120. 
98. 
98.4 
80. 
62. 


54. 
132. 

78.4 
88. 
78. 
70. 


50. 

98. 
58. 
72. 
56. 
56. 


42. 
88. 
62. 
74. 
42. 
60. 


32. 
76, 
46. 
56. 
34. 
51.2 



Water for Concrete. — Water for concrete should be 
perfectly clean, and free from organic and inorganic 
impurities. As regards the quantity, it can only be 
said that for such purposes as the foundations for pav- 
ing, casting blocks, &c., or where the material can be 
well rammed, so as to insure perfect consolidation, less is 
required than where the concrete can only be poured or 
laid in position. When mixed with sufficient water, the 
concrete occupies about one-eighth more space than when 



304 CEMENTS AND CONCRETES 

mixed with the full quantity, and percolation through 
the former gauge would be greater than through the lat- 
ter. Yet by thorough ramming the former would oc- 
cupy less space and offer greater resistance to moisture. 
An over-watered gauge is slow to set, difficult to work, 
liable to surface cracks, and often there is a loss of 
strength, caused by escape of a portion of liquid cement. 
The work will also be unequal in strength, owing to the 
• liquid cement flowing to various or lov/er parts, leaving 
parts of the aggregate bare and weak. 

It must not be inferred from the foregoing remarks 
that water is entirely unnecessary or of little value for 
concrete. On the contrary, it is of the utmost value. 
The evil is in the abuse, not in the use. Portland ce- 
ment has a great affinity for moisture. For instance, if 
a sack of cement is left on or in a damp place, a part of 
the contents soon becomes set and extremely hard, which 
is a proof of its affinity, and that moisture alone will 
set cement without water, far less excess of water. Fresh 
cement requires more water than stale cement. Cement 
gauged with sea water sets more slowly than with fresh 
water. Sea water should not be used in concrete in- 
tended for paving stables, chemical tanks, or similar 
places w^here it will come \n contact with ammonia. Sea 
water having a lower freezing-point than fresh water, is 
sometimes used in frosty weather to allow the work to be 
carried on. It ought not, however, to be used for ex- 
ternal work, especially for plastering facade as it has 
the property of attracting moisture and causing an ef- 
florescence on the surface. Sometimes in frosty weather 
hot water, also hot lime, is used for concrete; but al- 
though these hasten the setting and hardening of con- 
crete, they also wash away some of the finest and best 
particles of the cement during the gauging. A part of 



HOW TO USE THEM 305 

the water also forms in little globules throughout the 
mass, and when the water-drcps evaporate a series of 
small holes or bulbs are left, which deteriorate the 
strength of the concrete. Finally, it may be stated that 
the quantity of water required for gauging concrete is 
regulated by the class and condition of the aggregate, by 
the state of the atmosphere, and by the purpose for 
which the concrete is required. Another important point 
is the careful and thorough incorporation of all the ma- 
terials when gauging. A mass of raw materials^ if 
gauged carelessly, will require more water to attain the 
same plasticity than that which is carefully gauged. Ap- 
proximate quantities of water are given for Portland 
cement plastering. For concrete the quantity is about 
21 gallons of water to 1 cubic yard of dry materials, or 
about 1 part by volume to 8 parts. It is a good maxim 
to bear in mind when mixing water for concrete, that 
other things being equal, the minimum is better than the 
maximum. Water may be said to give birth to the 
strength of cement; to carry the simile further, the ag- 
gregate may be termed the bone, the matrix the skin and 
sinew, and the water the blood of concrete. 

Gauging Concrete. — It is a common idea that concrete 
can be gauged and used anyhow, with any aggregate, or 
with any amount of water ; and in consequence of a lax- 
ity in supervision in the selection of the materials, and 
their correct gauging and manipulation, unsatisfactory 
results are sometimes arrived at, the blame being at- 
tributed to the wrong cause. Gauging concrete re- 
quires considerable care to avoid waste of the materials 
and obtain the best possible work. Concrete can be 
gauged either by hand or by machinery. For small 
quantities, such as for stairs and similar work, the 
former is almost invariably used; and for large quan- 



306 CEMENTS AND CONCRETES 

titles, such as for foundations or buildings, &c., the lat- 
ter, being more economical, is preferable. A careful 
and uniform method should be employed for hard 
gauging; nothing should be left to chance or rule of 
thumb. The gauge-board should be sufficiently large to 
allow the materials to be turned over without spilling, it 
should be placed as near the work as possible, and it 
should be cleaned after each gauge. 

For fine concrete, no more than 1 cubic yard should be 
gauged at a time. This is as much as three men can 
properly gauge at once and m the proper time — that is, 
before the ''initial set" begins. Portland cement con- 
crete, unlike some mortars, does not improve by pro- 
longed working. If larger quantities are desirable, then 
more men must be employed in the gauging. All ma- 
terials should be measured for each gauge, to ensure uni- 
form setting and strength, and also the best work. This, 
combined with the saving of time and materials, will re- 
pay a hundredfold the cost of the measures. It is a 
common yet a w^rong way, when gauging for paving pur- 
poses, to measure the aggregate by so many barrowfuls 
to a sack of cement. Neither the aggregate nor the ce- 
ment can be accurately measured in this haphazard way. 
No man fills a barrow twice alike, and the cement being 
turned out of the sacks direct onto the aggregate is apt 
to vary, as it may contain lumps caused by damp, and 
very often some of the finest cement is retained in the 
sack, as more often than not it is simply drawn up and 
then thrown on one side without shaking it, as would be, 
cr at least should be done if the cement was emptied for 
air-shaking. The aggregate should be measured in a 
bottomless box or frame with handles at the ends, the 
cement in a box (with a bottom), and the water in a 
gallon metal measure or a pail made to contain 4 gal- 



HOW TO USE THEM 307 

Ions. Five pailfuls of this size are about sufficient to 
gauge 1 cubic yard where the concrete can be well 
rammed or punned. For work that is simply laid, 1 gal- 
lon extra is required. The box frame is laid on the 
gauge-board and filled with aggregate (in a damp state). 
The frame is lifted off, and the aggregate spread over the 
board until about 6 or 7 inches thick. The cement is 
then distributed over the aggregate. The materials are 
then gauged by three men, two with shovels, and one 
with a rake or larry, the former facing the latter. The 
dry materials should be carefully but energetically 
turned over twice or even thrice, and then when being 
turned over the third time water must be gradually ad- 
ded by means of a rose fixed on a water-can. Water 
poured from a pail is apt to wash parts of the cement 
away; the water also cannot be regularly and gradually 
distributed over the drv materials as when a rose is 
used. The mass is again turned over twice or even 
thrice, until thoroughly incorporated. This turning over 
does not consist of merely turning the mass over in the 
centre or on one place of the board, but to be effectively 
done a shoveller should stand at each side of the board, 
and the raker at the end to which the mass is to be first 
turned ; the shovellers lift the stuff and spread or rather 
scatter it on one end of the board with a jerking mo- 
tion, and the raker further mixes the stuff by working 
each shovelful backwards and forwards. This is repeat- 
ed, the stuff being turned to the other end of the board, 
after which it is turned to the center, the water being 
added as already described. The wet mass is then turned 
over twice in a similar manner, and finally finished in 
the centre of the board. The shovellers in the final mix- 
ing turn the stuff from the outside of the heap to the 
centre, while the raker gives the final touches. After 



308 CEMENTS AND CONCRETES 

being gauged, it should not be disturbed, but immediate- 
ly shovelled into pails, and conveyed to the place of its 
use. The ''initial set" begins nearly or as soon as gauged, 
and any after or unnecessary disturbance tends to de- 
stroy the setting properties of the cement. The practice 
of gauging, and afterwards regauging or knocking it up, 
is most objectionable, as it destroys its setting properties. 
No more should be gauged at one time than can be con- 
veniently laid in one operation. The gauging of this 
valuable material should not be left entirely to unskilled 
labor, but ought to be carried out under careful super- 
vision. 

Ramming Concrete. — The ramming, beating, or pun- 
ning of concrete is of great importance. It compresses 
the concrete, rendering it more dense and free from 
voids, and forces out all superfluous water. The re- 
sultant gain in strength, durability, and imperviousness 
is by no means to be despised. Without compression it 
is impossible to obtain impervious concrete. Prolonged 
ramming, however, is dangerous, as it may be contin- 
ued until the cement is set, which would be a direct loss 
of strength. For this reason, the ramming of concrete 
made with quick-setting cement should immediately fol- 
low the deposition of the material, and be expeditiously 
done. The concrete should always be gauged rather 
stiff than soft. If in the latter form, the ramming will 
separate the more fluid portions, and produce strata of 
different densities. When the concrete is deposited in 
layers, the joints of each layer, if dry or exposed, should 
be well swept and watered before the next layer is de- 
posited. It is often advisable, especially in very dry 
work, to brush the joints with liquid cement after they 
have been swept and wetted. For larger constructional 
work, the joints should also be keyed by aid of a pick, or 



HOW TO USE THEM 309 

by inserting stones at intervals into the concrete before 
it is setj leaving them projecting 3 or 4 inches above the 
level of the joint. Another method of forming a key is 
effected by forcing a batten on edge about 2 or 3 inches 
deep into the concrete, at the middle of the joint, and 
when the concrete is firm or nearlv set the batten is ex- 
tracted, thus leaving a groove which forms a key for the 
succeeding layer. 

No layer that has to be left for some time, or until 
dry, should be less than 4 inches deep. Thin layers are 
always a source of weakness. If the successive layers 
can be laid before the previous one is firm or set, the 
thickness is not of so much consequence. For large 
work, when each layer has to stand until set, the thick- 
ness may vary from 9 to 12 or even 18 inches. Ram- 
ming may be done by using an iron punner, or one made 
of hardwood and bound with iron. Wooden mallets 
and punchers or iron hand-floats are most suitable for 
ramming stairs and cast work. The gain in strength 
is shown in the table of the crushing strength of Port- 
land cement concrete. 

Thick7iess of Concrete Paving. — The thickness of con- 
crete paving laid in situ is regulated according to the 
purpose and the position of the work. The thickness al- 
so depends upon the nature and solidity of the founda- 
tions. It is obvious that a thicker paving is required 
for a foundation that is weak or soft than for one that 
is strong and hard. The best foundations are those com- 
posed of strong and well-laid rough concrete. Founda- 
tions composed of broken bricks or stone thoroughly con- 
solidated by ramming are the next best. The thickness 
of foundations is also regulated by the nature of the 
soil and the subsequent traffic. Paving for the sidewalks 
of mam streets, or where the traffic is heavy and con- 



310 CEMENTS AND CONCRETES 

tinuous, should not be less than 2 inches. For a medium 
traffic, and on a strong foundation, a thickness of 1^ 
inches will be sufficient. For side streets, garden paths, 
passages in houses, or similar places where the traffic is 
light and limited, a thickness from 1 to 1% inches will 
be ample if on a rough concrete foundation; but if on a 
dry ' ' dry, ' ' that is, broken brick or stone one^ the thick- 
ness should not be less than 1% inches. The thickness 
for stable floors may vary from 3 to 4 inches, according 
to the class of horses. For instance, a thickness of 3 
inches would be ample for race or carriage horses, but 4 
inches is necessary for heavy cart horses. The same 
rule applies to yards, a thickness of 3 or 3^/2 inches 
being sufficient for carriages, while 4 inches is required 
for carts, wagons, &c. Factory floors are generally made 
2 inches thick, but where there is machinery or wheel 
traffic a thickness from 2% to 3 inches is employed. By 
computing the volume and nature of the traffic, and 
comparing the tests of concrete paving given herein, the 
requisite thickness will be readily obtained. It must of 
necessity greatly depend on the class of the materials 
and manipulation used for the paving. Like most other 
articles, a good material will go further and last longer 
than a bad one. 

Concrete Paving. — Good pavements proclaim a city's 
progress. Isodorus states that the Carthaginians were 
the first people to pave streets. The subject of paving 
and floors will be best understood by dividing it into two 
parts — namely, paving, which is a floor surface laid and 
resting on solid ground; and floors, by which are meant 
floors over voids. The following items briefly embody 
the processes used for most concrete pavings now in 
use. Paving in situ is either laid in ''one coat" or 
*Hwo coats," the latter being in more general use than 



HOW TO USE THEM 311 

the former, yet each method has its individual merits. 
One-coat work is not so liable to rise or laminate as two- 
coat work. It takes slightly less labor, the whole thick- 
ness being laid in one operation. The aggregate is 
either granite or slag, or both in equal proportions, 
gauged with Portland cement in the proportion of 2 of 
the latter to 5 of the former. Two-coat is laid with 
two different aggregates and gauges. The first coat has 
a cheap aggregate, such as ballast, clinkers, bricks, or 
whinstone, broken so that they will pass through a 1 
inch mesh riddle, and gauged in the ratio of 1 of Port- 
land cement to 5 of the aggregate. It is laid till within 
1 inch of the finished surface. The second coat is laid 
as soon as the first is set, and is composed of 1 part of 
Portland to 2 of the aggregate, the latter being either 
crushed granite, slag, limestone, or whinstone that will 
pass through a 3-16 sieve. In some districts fine shingle 
is used for the topping aggregate. 

Quick-setting solutions are used to reduce the time re- 
quired to allow the paving to harden before it is avail- 
able for traffic. Many pavements are ruined by being 
used before having become sufficiently hard and set. 
Many of the so-called quick-setting materials have the 
desired effect of setting the concrete quickly, but the 
work in many cases is none the better for these solutions. 
On no account should these quick-setting materials be 
used, unless thoroughy tested and the concrete proved 
durable by use and time. In order to protect the sur- 
face and allow the paving to be used immediately, P. M. 
Bruner, an American engineer and concrete specialist, 
covers the surface of the pavement directly it is finished 
with a thin coat of plaster or Parian cement, which ad- 
mits of walking upon in a few hours, and resists pedes- 



312 CEMENTS AND CONCRETES 

trian traffic until the surface proper is sufficiently hard, 
after which it is shelled off with a trowel. 

Eureka Paving. — This is the name for an improved 
concrete, which has been extensively used with good re- 
sults for many purposes, such as pavements, floors and 
stairs. Eureka, if not exactly one-coat work, is nearer 
that than two-coat work, and may be said to be the 
happy medium, or a combination of both. Eureka is 
laid in two layers. The first is termed the "rough 
coat," and 'the second the "fine coat" or "topping." 
The topping is laid nearly as soon as the rough coat is 
laid, just as in rendering or dubbing-out plaster work. 
The materials and gauges are nearly alike for both 
layers. The gauged rough stuff is laid on the founda- 
tion, previously wetted to prevent suction, and spread 
and beaten with an iron hand-float. The laying, spread- 
ing and beating is continued until the rough surface 
is within % inch of the finished line. The surface of 
the rough coat is made fair, and a uniform thickness 
for the topping is obtained by passing a "gauge-rule" 
across the surface. A uniform thickness of topping 
gives an equal expansion, therefore the surface is not 
liable to crack. The suction is also more regular, which 
permits of the trow^elling to be done with greater free- 
dom, and without causing hard and soft places on the 
surface. 

As many alternate bays are laid as will allow of all 
being topped and finished the same day. When the 
number of bays to be laid in on one day has been de- 
cided, and the last one roughened in, the first bay will 
be firm to receive the topping. The topping is laid and 
spread with a wooden hand-float, ruled and trowelled 
and brushed as afterwards described in the general pro- 
cess. This method of laying a part of the thickness o± 



HOW TO USE THEM 313 

the paving, gauging stiff and beating the mass, forces 
it into the interstices of the broken dry foundation, and 
not only consolidates the foundation and the rough coat, 
but also forms a solid bed to receive the topping. The 
topping goes in sooner and more regularly on a stiff- 
gauged and well-beaten coat than on a soft-gauged one, 
or than if the whole thickness of the paving were laid 
in one coat. 

Eureka Aggregate. — The method of preparing the ag- 
gregate for Eureka is of the utmost importance. The 
labor expended on its preparation is more than repaid, 
not only in the ease and rapidity when finishing, but also 
in the satisfaction of doing a strong and workmanlike 
job. Slag and granite is far more preferable to gravel 
or stone as an aggregate. Slag and granite in equal 
proportions have been used with good results. The size 
ordered from the furnace or quarry should be % inch 
screenings. It must be washed through a % i^ch sieve 
in a tub or iron tank. The coarse part rejected by the 
sieve to be laid aside for the rough coat. The fine ag- 
gregate is then washed again through a fine sieve to ex- 
tract any mud or impalpable powder, as the presence of 
such impurities weakens the consolidating power of the 
cement, and decreases the ultimate strength of the con- 
crete. This fine aggregate for the topping should be 
angular and of various graduating sizes, from that of 
fine sharp sand to the largest size that has passed through 
the % inch sieve. It has been proved by experience and 
the test of time that an artificial stone made with a fine 
aggregate has not only more resemblance to the grain or 
texture of natural stone, but is also denser, and wears 
better and with more uniformity, than one made with a 
large, round, or equal-sized aggregate. The use of small 
and angular aggregate of the graduating sizes ensures 



314 CEMENTS AND CONCRETES 

their fitting closer and interlocking together, thus form- 
ing a stronger bond, giving a regular key and freedom 
for each separate piece to be coated with cement, the 
whole forming a solid and homogeneous body with a 
hard surface. Concrete with large or round aggregate, 
and the various pieces disproportionate in size to each 
other, will fit loosely and unevenly, and only touch at 
their most prominent points, thus leaving voids, and con- 
sequently unsound work. The voids may perchance be 
wholly or partly filled with matrix, still this is an un- 
necessary waste of cement. Consequently, concrete pav- 
ing having large or round aggregate wears unevenly, and 
leaves the large or round pieces uncoated and loose, or 
so exposed above the surface that they soon get dis- 
lodged, leaving a series of small holes, which sooner or 
later wear larger and larger. Another point of import- 
ance is that concrete with a fine hard aggregate is more 
plastic, works freer, and has a greater compressive 
strength than concrete with a large or soft aggregate. 
Eureka concrete, having a fine^ clean, and regulated ag- 
gregate, should be used for the topping of paving, steps, 
landings, or for any class of work exposed to friction or 
wear. It is well to remember that a good matrix will 
not make a bad aggregate strong, although a bad ag- 
gregate will make a good matrix weak, or rather the re- 
sultant concrete weak. 

Eureka Quantities. — The quantities for the rough 
coat are 1 part of Portland cement and 4 parts of the 
coarse portion of Eureka aggregate. These materials 
must be gauged stiff, only as much w^ater being used as 
will allow the mass to be thoroughly mixed and plastic. 
The quantities for the topping are 2 parts of Portland 
cement to 5 of the fine aggregate, and gauged about the 
consistency of well-tempered ''coarse stuff," as used for 



HOW TO USE THEM 315 

floating. Experiments prove that neat cement is infe- 
rior in wear-resisting qualities (such as frictional wear 
and pedestrian traffic) to mixture of cement with sand 
or other aggregate, being in fact equal to a mixture of 
about 1 part of cement to 3 parts of aggregate. The 
best wearing qualities are obtained by a mixture of 2 
parts of cement to 3 of aggregate. 

Levels and Falls. — Accurate levelling and adjustment 
of the requisite falls are important features for pave- 
ments and flooring. Levelling is the art by which the rel- 
ative heights of any number of points are determined. 
Falls are used to allow rain and water used for cleansing 
purposes to run off into channels and drains. The levels 
and falls in good buildings are generally marked, on the 
drawings, but it is imperative that the worker should be 
conversant with the necessary amount of falls for paving 
purposes, as many unforeseen difficulties often arise in 
this class of work, especially in large surfaces. The most 
accurate and speedy way of setting out levels and falls 
is of special service to concrete paviors. The importance 
of these features will be readily appreciated, especially 
where these paving preliminaries are left to the care of 
the concrete layers. The amount of cross fall for street 
pavements varies according to the class and position of 
the work. The fall is also regulated by the gradient. For 
a level stretch of paving it is generally 1 to 60, therefore 
for a pavement 6 feet wide it would be 1 inch. The fall 
for rising ground is usually % inch for every 2 feet in 
the width of the pavement. The falls for stables and 
yards are given under their respective headings. The 
points for levelling — also for falls — are formed by driv- 
ing wooden pegs into the ground at the most suitable 
points. The heads of the pegs represent the finished face 
of the pavement. They are made level with each other 



316 CEMENTS AND CONCRETES 

by the aid of a parallel rule and a spirit-level. Inter- 
mediate pegs may also be levelled by means of boning 
rods. 

Pavement Foundations — Good foundations for con- 
crete paving are of primary importance, and unless the 
bottom is firm, and the foundation is sound, the best 
made and laid concrete will subside, crack, and be per- 
manently spoilt. Pavements generally cover a large 
area, and the superstructure, however strong, must have 
a firm foundation. Foundations consist of two parts — 
the first is the bottom ground or natural foundation ; the 
second is the made-up or artificial foundation; but for 
simplicity the first is termed the "bottom," and the lat- 
ter the "foundation." The latter may be "dry" or 
"gauged." If the bottom is soft, it must be well ram- 
med before laying the dry materials for the foundation, 
or a layer of common coarse concrete for gauged work. 
When excavating the ground to receive the foundation, 
the depth from the intended finished surface of the 
pavement should be about 5 inches for paving 2 inches 
thick, 6 inches deep for paving 2% inches thick, and 7 
inches deep for paving 3 inches thick. The above depths 
are for dry foundations, and where the traffic is light, 
such as side-walks, playgrounds, and passages. If the 
bottom is soft, or the paving intended for heay>^ traffic, 
the depths may be increased, and the bottom well ram- 
med before the materials are laid. The materials for the 
dry foundations are broken bricks, stone rubblCj or other 
hard core. They should be spread on the bottom, and 
broken in situ. The breaking in situ tends to consoli- 
date the bottom and the foundation. When broken, no 
piece should be left that will not pass through a 2% inch 
ring. If the paving is intended for heavy traffic (carts 



HOW TO USE THEM 317 

or the rolling of heavy casks) it is best to have a rough 
concrete foundation. The rough concrete should be 
from 4 to 7 inches deep, according to the firmness of the 
bottom and class of traffic. This concrete is composed 
of ballast or equal parts ballast and broken bricks, coke- 
breeze, or hard clinkers, gauged in the proportion of 1 
of Portland cement to 5 or 6 of aggregate. It should be 
laid to the desired fall. If lime instead of Portland ce- 
ment is used for the rough concrete, great care should 
be taken to thoroughly damp the surface, and allow a 
sufficient time for the lime to expand and any lumps of 
unslaked lime to slake, before the fine concrete is laid. No 
paving should be laid until the rough concrete is thor- 
oughly set. Allowance must also be made for any set- 
tlement of the bottom, and for any subsidence, contrac- 
tion, or expansion of the concrete foundation. The 
rough is not so liable to contraction or expansion as fine 
concrete, but it is more liable to subsidence. Expansion 
is due to the cement not to the aggregate ; and as there is 
less cement in rough concrete than in fine, it has less 
power of expansion, and owing to the greater amount 
and weight of aggregate, there is the lesser power of con- 
traction. The size of aggregate for rough concrete is 
also larger than for fine; consequently each piece offers 
a greater resistance to the cement. Subsidence is due to 
the settlement by gravitation of the aggregate to the bot- 
tom, which takes place after the excess water, or even 
the liquid cement, has percolated through voids or spaces 
of badly made or laid concrete. Unequal subsidence is 
caused by bad and unequal gauging; one gauge being 
firm, keeps in position ; while if soft and sloppy, the ex- 
cess water either settles in the deepest places, or escapes 



318 CEMENTS AND CONCEETES 

into the ground, thus allowing the body of the concrete 
at those parts to subside. 

Screeds and Sections. — Screeds are used as guides and 
bearings for leveling and ruling off. They are general- 
ly formed with wood rules, planed on all sides, and in 
suitable sizes, and are termed "screed rules." Screeds 
are sometimes formed with the same kind of material as 
used for the pavement, and are termed ' ' gauged screeds. ' ' 
Screed rules give the best results ; they are speedily laid ; 
can be used at once, and form a clean and square joint 
when laying work in sections. Screed rules are tempo- 
rarily fixed on the foundation by laying them on narrow 
strips of gauged concrete, and then made straight, and to 
the proper falls, by laying the edge of a straight-edge on 
them, and tapping with a hammer till firm and true. 
When the bay is finished and set, the screeds are re- 
moved by gently tapping with a hammer, leaving a clean, 
straight, and square joint. Where there is only a small 
quantity of screeds required, or where time wdll not per- 
mit of waiting for the concrete bedding strips to set, the 
screed rules can be fixed on gauged plaster, which al- 
lows the screeds to be used at once. The plaster should 
be cleaned off at the side intended to be laid, to ensure a 
sound bed for the concrete, and a square joint. Gauged 
screeds may be also formed with gauged coarse plaster. 
They are best done as described for "pressed screeds." 
In laying large surfaces it is best to arrange the screeds, 
so that the work can be laid in alternate sections or bays, 
which will afford greater facility to get at the work, and 
also to allow the isolated bays to expand. For instance, 
if laying a stretch of paving 50 feet long and 6 feet wide, 
this would be laid out in 5-feet bays, the screed rules, 
each 6 feet long, being laid so as to form the odd num- 



HOW TO USE THEM 



319 



bered bays to be laid and finished first. This allows the 
workmen more freedom by standing on the empty bays 
when finishing the laid bay. The screeds are then re- 
moved, and the intermediate bays laid, the sides of the 
finished bays serving as screed or bearing when ruling 
in. Boards or bags are laid on the finished bays to pro- 
tect the surface, and give a footing for a workman to 
finish off the intermediate spaces. It must not be for- 
gotten to fix the screed rules toward the curbs, also to 
keep the ends of the screed about % inch about the curb, 
to allow for any subsidence, and for the water to run 
off. This also provides for the greater amount of wear 




Sections of Concrete Kerb, Channel, and 
Paving. 

NO. 1. 



that takes place near to than actually on the curb. The 
foundations should be thoroughly saturated with water 
before the screeds are fixed. If this is not done, the 
brick or other dry material used will absorb the moisture 
or life from the concrete, and render it dry or dead. The 
drenching with water also frees the broken materials 
from the dust caused by breaking the large pieces in 
situ. In laying paving or a gauged foundation, the sur- 
face should be well swept with a hard broom and after- 



320 CEMENTS AND CONCHETES 

wards damped, so as to ensure the perfect cohesion and 
solidity of the foundation and the paving. The curbs 
and channels are sometimes made in situ, but more often 
they are cast and laid in the same manner as ordinary 
stone. Cast work is harder than laid work; it also al- 
lows the paving to be laid with greater freedom. Illus- 
tration No. 1 shows sections of the street curbing and 
channel which may be used in connection with slab pav- 
ing, or pavements laid in situ. 

Laying Concrete Pavements. — The foundations having 
been damped, and the rough stuff gauged, it is carried 
in pails and emptied at the top end of the bay. The plas- 
terer spreads it with a layer float, and rams it well into 
the foundation. When he has laid a stretch the whole 
width of the bay, and as far as he can conveniently reach, 
he moves back and lays the remaining portions of the 
bay in the same way until complete. The rough stuff 
surface is then made fair, but not smooth, with the gauge 
rule. The remainder of the bays are dealt with in rota- 
tion. The fine aggregate is then gauged, and laid and 
spread until flush with the screeds. The stuff should be 
rather above than below the screeds, to allow for subsi- 
dence by subsequent ramming, ruling and patting. All 
concrete bodies over 2 inches thick should be deposited 
in layers. Each layer should be well rammed with an 
iron, or hardwood temp, bound with iron. Concrete 
gains strength by compression, and consequently its 
density, imperviousness, and durability are increased. 
Even for 2 inch pavement better results are obtained if 
the stuff is deposited in two layers, each layer well 
beaten with an iron hand-float. If only 1% inches thick, 
it should be consolidated by being beaten with an iron 
float. The surface is next ruled with a floating rule. 



HOW TO USE THEM 321 

The rule is worked square or edge, and the concrete cut 
and beaten in successive short and quick strokes. If the 
stuff is soft and laid too full, the rule is worked loosely 
on edge with a zigzag motion, so as to draw the excess 
stuff and water off the surface, and leave the body full 
and regular. If there are any hollow places, they are 
filled up with stuff, and the rule again applied. In all 
cases the surface should be finally straightened by beat- 
ing with the rule. This process leaves the surface more 
uniform, straight, and solid than by dragging or working 
the rule. 

Trowelling Concrete. — After being ruled, and when 
slightly firm, the surface is beaten with a wood hand- 
float, which lays any irregular parts or projecting pieces 
of aggregate. The beating or patting is continued until 
the "fat" appears on the surface. It is then trowelled, 
or rather ironed, the trowel being worked on the flat of 
the blade with a circular motion. The plasterer, when 
trowelling off, should have a hand-float in the other 
hand to lean on when reaching to a far off part. The 
float is also useful to pat any dry parts. The surface 
must be finished with a semi-dry stock-brush to obtain a 
uniform grain. A vast amount of care is required in 
trowelling off'. Perfection can only be attained by prac- 
tice, and a clcse observation of the materials, conditions, 
and the state of the atmosphere during the progress of 
the work. The best effects can only be attained by 
acquiring a knack of working the trowel on the flat, and 
by knowing when to begin and when to leave off. It is a 
waste of time, and the cause of an unequal surface, if 
the trowelling is begun before the stuff is firm; but time 
and labor will also be lost if the trowelling is left until 
the stuff is too stiff, or has nearly set, for then the sur- 



i^22 CEMENTS AND CONCRETES 

face will be rough and patchy. In either instance th© 
surface is more or less spoilt, and the ultimate appear- 
ance and hardness seriously affected. 

Grouting. — The use of neat cement for trowelling off 
should not be resorted to (this is termed "grouting"), 
and is used when the surface is left till set, or when it 
has not been properly patted and trowelled. The ex- 
pansion of a strong and weak gauge being unequal, the 
result is that the surface peels, or should it adhere, it is 
patchy and discolored. Where grouting is unavoidable, 
the cement should be gauged with an equal part of fine 
aggregate, the aggregate being the same as used for the 
topping. 

Dusting. — Another bad process is that of sprinkling 
dry neat cement over a soft surface (this is termed 
*' dusting"), and is used to absorb the moisture caused 
by sloppy gauging. It has drawbacks similar to grout- 
ing. If unavoidable, the cement should be mixed with 
line dry aggregate in the same proportion as the topping. 
If the stuff were trowelled at the correct time, there 
would be no necessity for grouting; and if properly 
gauged, no need for dusting. No concrete surface can be 
made so solid and hard as when it is finished in one body 
and at one time. 

Temperature. — It is well known that extreme heat and 
cold effect the expansion and contraction of iron. These 
extremes have a similar effect on concrete, especially dur- 
ing the process of setting and hardening. Equality of 
temperature during setting is desirable. Cold and 
humid atmosphere retard setting; hot humidity acceler- 
ates it. Concrete laid in cold weather stands better 
than that laid during hot. Concrete laid in mild damp 
weather is better than in either extreme. During high 



HOW TO USE THEM 323 

temperatures, the surface, when sufficiently hard, should 
be covered with damp deal saw-dust, old sacks, mats, or 
sail-cloth, and saturated at intervals with water. If the 
sun's rays are hot, the surface of the work while in 
progress should be protected by extending tarpaulin or 
sail-cloths above the parts being laid. Concrete surfaces 
are further hardened by flooding with water, or where 
this is not practical, covering with wet saw-dust or sand 
as soon as set. Care must be taken that the saw-dust is 
clean and of a light color, as otherwise it will stain the 
work. 

Non-Slippery Pavements. — Concrete pavements for 
special purposes are rendered non-slippery by mixing Vg 
inch lead cubes with the topping stuff. Lead cubes about 
1/^ inch square laid by hand from 1 inch to 4 inches 
apart in the moist concrete surface, have been used for 
rendering concrete surfaces non-slippery. Iron and 
brass filings are also used for the same purpose, and also 
for increasing the wear-resisting of concrete surface. 
Roughened, indented, grooved, and matted surfaces are 
also used to obtain a better foot-hold on concrete sur- 
faces. 

Grooved and Roughened Surfaces. — Stables, yards, 
&c., are grooved and channeled on the surfaces to pre- 
vent animals from slipping, and also to carry off urine 
or other liquids to the traps or gulleys. Indented sur- 
faces are useful on steep gradient to give a better foot- 
hold. Grooves are made with a special wood or iron 
tool, which is beaten into the surface as soon as the con- 
crete is floated. The grooves for stables are generally 
made about 5 inches from centre to centre, and the depth 
about % inch. A line is first made at the one end of the 
work, and the groover is then laid on this line, and beat- 



324 CEMENTS AND CONCRETES 

en down with a hammer to the desired depth. Before it 
is taken off, a parallel rule is laid on the surface and 
against the groover, which is then taken up and laid 
close to the other side of the parallel rule, and beaten 
in as before, and so on until the whole surface is done. 
The width of the parallel rule, is equal to the desired 
width between the grooves, less the width of the groover. 
Grooves, however long, can be made by moving the tool 
along, and against a long parallel rule. After stretch of 
grooves have been sunk, the surface is trowelled, and the 
indentations made true. It may be necessary to apply 
the groover again, and beat or work it forward and back- 
ward and further regulate their depth and straightness. 
They are then made smooth with a gauging trowel and 
finished with a damp brush, the sides of the grooves being 
left smooth to give a free passage for liquids. 

Grooves on a surface having a fall should radiate to- 
ward the deepest point. A level surface may be made 
to carry off the water by the indentation being formed 
wider and deeper towards the outlet. Street and other 
pavements are sometimes indented with metal rollers to 
give a better foot-hold. Platforms and other surfaces are 
sometimes made rough or indented by beating the moist 
concrete, with a '^ stamping-float. " The sole, has a series 
of squares projecting about % inch, each square about 
1 inch, and a half inch apart. Concrete surfaces are al- 
so roughened or matted by dabbing the surface as soon 
as trowelled with a coarse stiff whale-bone brush. Illus- 
tration No. 2 shows three designs of grooved surfaces for 
carriage drives, conservatories, &c. A plain border, or 
one with a single width of the main design, is generally 
formed on the sides and ends of the floor. A rough mat- 



HOW TO USE THEM 



325 



ted surface may also be obtained by pressing or beating 
a wet coarse sack or matting over the moist concrete. 

Stamped Concrete.— Various materials and methods 
are used for stamping or indenting concrete surfaces to 
obtain a better foot-hold, or to form any desired pattern. 
Iron stamps are generally used, but owing to their 
weight and rigid nature, are unsuitable for large sec- 



Fig. I. 



Fig. 2. 



Fig- 3. 



\ ~ ' 




1 1 • 


r 1 


1 1 . _ . 


"I 


1- 


1 


"T3'""F 


1 


1 


■ L. 


„.3J 1 ^ 







tfTtii'. 



Three Examples of Grooved Surfaces. 
NO. 2. 

tions. Plaster stamps are sometimes used for temporary 
purposes, or for small sections and quantities. Stamps 
for large concrete surfaces should be composed of a ma- 
terial that is easily made to the desired form durable 
and slightly flexible. 

Expansion Joints. — Compressive or flexible joints are 
used to allow for any expansion or contraction that may 
take place in a large area of concrete exposed to atmos- 
pheric changes. There are various methods in use for 



B26 CEMENTS AND CONCRETES 

the purpose. The first is to set out the area in small 
sections, and to lay them in alternate or isolated bays, 
thus giving time for their expansion before the inter- 
mediate bays are laid. This method, by dividing the 
area into small sections, is the best for preventing cracks, 
because small sections are stronger than large ones ; and 
in the event of any subsidence in the foundation, the 
surface fissures are limited to the immediate joints of 
the section. Contraction and expansion is also less in 
small bodies than in larger ones. 

Another method of forming joints is by cutting with a 
wide chisel or a cutting tool before the rough concrete is 
set, a corresponding joint being cut in the fine concrete 
topping. False joints are made by indenting the top- 
ping after it is trowelled, A metal roller is used for 
finishing true joints and forming false joints. Frame 
strong enough to resist the expansion of the concrete 
would not only increase the density and strength of 
concrete paving and blocks, but also effectually prevent 
its cracking. 

Another method for forming sections in large sur- 
faces of pavement of floors to prevent cracks is effected 
thus: — first set out the size of proposed sections on the 
rough or first coat, then with a straight-edge, a wide 
chisel, or a cutting tool and a hammer, cut through the 
rough coat, so as to divide it into sections as set out. 
This done, insert wood strips into the cutting, keeping 
their top edges about % inch below the screeds or rules 
which represent the finished surface. The strips are 
made from % to 1% inches wide, 3-16 inch thick, and in 
suitable lengths. The width is regulated according to 
the thickness of the paving. For instance^ for two inch 
paving the widths should be 1% inches. This allows 



HOW TO USE THEM 



327 



about % inches in the rough coat (with % inch play 
from the bottom), and about % i^ch in the topping, and 
% inch for the upper thickness of the topping to cover 
the top edges of the strips. After the strips are inserted 
the rough coat is beaten up or made good to the sides of 
the strips, and then the topping is laid and trov/elled in 
the usual way. The surface joints are then made direct- 




'• •• 

SECTION 

-Half Plan of Coach Yard, with 
Section through Centre. 

NO. 3. 

ly over the strips, with the aid of a straight edge, so as 
to form a clean and sharp joint. As already mentioned, 
these strips allow for any subsequent contraction or ex- 
pansion, thus avoiding zigzag cracks ; and in the event of 
repairs to underneath pipes, each section can be cut out 
and relaid separately without injury to the adjoining 
sections. This process of inserting strips in the rough 
coat, cutting nearly through the topping, gives the same 
results as if the strips were laid flush with the surface 
of the topping, with the advantages that the surface can 
be more readily trowelled, and is more pleasing to the 



328 CEMENTS AXD COXCEETES 

eye. because the strips are not seen. A cutting tool is a 
blade of steel about 5 or 6 inches long and 4: inches wide, 
with a wood handle at one end. The section of the blade 
is well tapered, so as to obtain a sharp cutting edge, and 
form a wide top edge to offer a broad surface for the 
hammer while being beaten. 

Washing Yards.. — Eureka concrete being of a hard 
nature, and having a close and smooth surface, is well 
adapted as a flooring for all washing or cleaning pur- 
poses. The surface being smooth, it can in turn be read- 
ily cleaned. Illustration Xo. 3 shoAvs the half plan of 
washing yard for washing carriages, &c. 

Stahle Pavements. — The paving for stables, and other 
places for keeping animals, should be jointless, non-ab- 
sorbent, hard, and durable. Such paving must not be 
slippery, yet smooth enough to be easily washed, the 
whole laid to falls, and grooved to sive an easv and 
ready passage for liquid manure and water when being 
washed. Xo material can so fully meet these require- 
ments as a well-made and well-laid concrete. Granite 
sets are hard, but slippery. Bricks are too absorbent; 
the urine percolates between the joints and generates 
ammonia and other efflu^ua which are detrimental to the 
health of the animals. (See Xos. 4 and 5.) 

Stables are generally laid with a fall toward the main 
channel. The amount of fall varies according to ideas 
of the horse ownei^. The fall adopted by the War office is 
1 in SO from the top of the manger to the main channel, 
and 1 to 36 from each side of the stall to the centre groove. 
The -width of the main channels is usually set out with 
screed rules, which also act as screeds to work from. 
Channels are generally formed after the other surface is 
finished. Sometimes templates are fixed on the bed of 



HOW TO USE THEM 



329 



the channels, and the space filled in and ruled off with a 
straight-edge while the whole surface is being formed. 
The thickness of stable paving varies from 2 to 314 
inches, according to the class of horse. The thickness of 
the stalls is often decreased toward the manger. 

The most useful length is 2 feet 6 inches. They can 
be cut with a chisel as easy as cutting stone. Special 
slabs can be made for circular work, also with rebated 
sinking for metal plates, to cover coal-holes, drains, gas 
and water taps, &c. Concrete paving slabs are laid in 
precisely the same way as natural stone. 




jjecfion of side crraves C 
Section, cf Channel, a? S 




y ^ 




TanTfeTTu^lTt iron cproTf Section of centre grova 2> 

-Sections of the various Parts of the Stable Floors 
SHOWN ON Illustration 



NO. 4. 



NO. 5. 



Concrete Slab Moulds. — Slab moulds are made with 
1% inch boards lodged together. On this ground, wood 
sides and ends (each being 2% inches by 2 inches, or 3 
inches by 3 inches, according to the desired thickness of 
slab) are fixed. One side and end is held in position 
with thumb screws, which fit into iron sockets, so that 
they can be unscrewed to relieve the slab when set. The 
bottom and the sides and ends are lined with strong iron 
or zinc plates. 



330 CEMENTS AND CONCRETES 

Slab Making. — Slabs are mostly made by machinery. 
The materials are 1 part of Portland cement mixed dry 
with 21/2 parts of crushed granite and slag in equal pro- 
portions that have been washed and passed through a i/4 
inch sieve. They are thoroughly incorporated together 
in a horizontal cylinder worked by machinery, a mini- 
mum of water being added, and the mixing continued 
until the mass is well gauged. The mould, which has 
been previously oiled, is placed on a shaking machine 
known as a " trembler " or ' ' dither, ' ' which gives a rapid 
vertical jolting miotion to the mould and its contents. A 
small portion of "slip," that is, neat cement, is laid 
round the angles. The machine is then started, and the 
concrete laid on the mould by small shovelfuls at a time, 
a man with a trowel spreading it over the mould until 
full. The surface is then ruled off. If both sides of the 
slabs are required for use, the upper surface is trowelled. 
The whole operation of mixing, filling in, and ruling off 
takes about seven minutes. The filled moulds are re- 
moved and allowed to stand for about three days. The 
slabs are then taken out, and stacked on edge and air- 
dried for about five days. They are then immersed in 
a silicate bath for about seven days, and are afterwards 
taken out and stacked in the open air until it is required 
for use. They should not be used until three months 
old. Paving slabs are also made by hand, by ramming 
and beating the moist concrete into the mould with an 
iron hand-float. Powerful ramming, trituration, or vio- 
lent agitation of the gauged material in the mould, tend 
to consolidate concrete, and it is possible to further in- 
crease homogeneity by the use of hydraulic pressure. 

Induration Concrete Slabs. — The surface of concrete 
slabs or other work exposed to friction or wear may be 



HOW TO USE THEM 331 

hardened by soaking in a silicate solution. Silicate of 
soda has a great affinity for the materials of which con- 
crete is composed, and by induration causes the surface 
to become hard, dense, and non-porous. 

The silicate of soda and potash is known as soluble 
glass or dissolved flint. The soluble silicate is a clear 
viscous substance made from pure flint and caustic soda, 
which is digested by heat under pressure indigester. Its 
strength is technically known as 140 degrees, which 
shows 1,700 on a hygrometer. When used as a bath for 
concrete, it is diluted with water, the proportion vary- 
ing from 6 to 10 parts of water to one of silicate. Con- 
crete pavements, laid in situ, may also be hardened by 
washing with silicate solution. They should not be sili- 
cated until two days after being laid, to allow the mois- 
ture to evaporate and the silicate to penetrate. 

Mosaic. — The art of making mosaic is at the present 
time scarcely within the province of plasterers, but in 
former times many kinds were made in situ or in slabs 
by plasterers. The subdivision of labor has to a great 
extent caused mosaic-making to be confined to special- 
ists. Concrete is still made by plasterers. A brief de- 
scription of this and other kinds may prove useful as 
well as interesting, especially to plasterers who are in 
the habit of fixing tiles and working in concrete. Mosaic 
is the art of producing geometrical, floral, or figured de- 
signs, by the joining together of hard stones, marbles, 
earthenware, glass, or artificial stone, either naturally 
or artificially colored. The term ''mosaic" embraces a 
wide range of artistic processes and materials for the 
decoration of floors, walls, ceilings. The Egyptians were 
experts in mosaic. The Cairo worker as a rule had no 
drawings made beforehand, but the mosaic design was 



332 CEMENTS AND CONCRETES 

constrncted by the artist as he arranged the pieces on 
the ground. The mosaic pavements of Cairo are of a 
slightly different character from those used for wall 
decoration, and are generally composed entirely of mar- 
ble tesserae (and sometimes red earthenware) of larger 
size than the delicate pieces included in wall mosaics. 
They are arranged to form geometrical patterns within 
a space of about two feet square. Each square slab is 
made separately, and the pieces are set, not in plaster, 
but in a composition of lime and clay impervious to 
water. The clay must be unbumt, just as it comes from 
the pit. Saracenic mosaic in Egypt is a combination of 
the tesselated method with a large proportion of sectile 
mosaic. The Romans also were great workers in mosaic. 
The mosaics of Byzantium and Ravenna consisted of 
cubes of opaque and colored glass. 

The general method used here for pavement mosaic is 
as follows : The repeated design is traced on stout paper 
and small pieces of marble, or more often tile, are 
gummed on the paper, following the design of form and 
color, one piece at a time (with the smooth face down- 
wards) being laid until the design is completed. The 
mosaic slabs, which are thus temporarily kept in posi- 
tion, are sent to the building and laid where intended. 
A rough concrete foundation, which has previously been 
made level, is then floated with Portland or Keen's 
cement, and the slabs with paper are then damped and 
drawn off, and any openings or defects filled up with 
small pieces of the same form and color as the design. 
The slabs are made in various sizes 'according to the de- 
sign. For instance, a border 12 inches wide may be made 
from 3 to 6 inches long. When laying the slabs, it is best 
to begin at the centre and work outwards, and any ex- 



HOW TO USE THEM 333 

cess or deficiency taken off or made up in the plain part 
of the border at the walls. The tiles are made at pottery- 
works in the required sizes and colors. The thickness is 
generally about % inch and the average surface size 
about % inch. Females are often employed fixing the 
pieces on the paper. The designs of coats of arms, mono- 
grams, dates, figures, flowers, and foliage are effectively 
produced by this simple and cheap process. 

Concrete Mosaic. — All mosaics are more or less of a 
concretive nature, and the trade term of "concrete mo- 
saic" is due to the fact that the matrix used is Portland 
or other cement gauged with the marble aggregate, and 
laid in most cases in a similar manner as ordinary con- 
crete. Concrete mosaic is extensively used for paving 
halls, corridors, conservatories, terraces, &c. It is also 
used for constructing steps, landings, baths, pedestals, 
&c. Slabs and tiles made of this class of mosaic for 
paving purposes are slowly but surely proving a for- 
midable rival to Italian mosaic encaustic tiles. It can 
be made in larger sections, thus facilitating rapidity of 
laying. It is more accurate in form^ durable, non-slip- 
pery, and cheaper. The last reason alone is a favorable 
item in this keen age of competition. Where marble has 
been scarce, broken tiles, pottery, colored glass, flints, 
white spar, &c., have been used as aggregate. If the 
marble chips are obtainable as a waste, and near the place 
of manufacture, the primary cost is small. If the moulds 
are of metal, and made in sections so as to form a series 
of moulds in one case, and the casts are pressed by means 
of a hydraulic power, the cost of production is reduced 
to a minimum. If the casts are polished in large num- 
bers by machinery on a revolving table, the total cost is 
further reduced. For local purposes they can be made 



334 CEMENTS AXD COXCKETES 

bv hand at a medium cost. Slabs are made in almost 
any size, but generally from 4 to 6 feet superficial. The 
thickness varies from 1 to 1% inches. Tiles are usually 
made about 10 inches square and 1 inch thick. The tiles 
are generally made with a face of cement and white mar- 
ble, or white and black marble chippings. They are 
backed up with a cheaper aggregate. Various tints of 
the face matrix are obtained by mixing the cement with 
metallic ovides. The tiles are made in wood or metal 
moulds, with metal strips to form the divisions of form 
and color in the design. If the design is fret pattern, 
the gauged material is put in between the strips that 
form the band of the fret. When the stuff is nearly set, 
the strips are taken out, and the other part filled in with 
another color. Sometimes the band or running designs 
are cast in a separate mould, and when set placed in posi- 
tion in a larger mould, and the ground filled in, cover- 
ing and binding the whole in one tile. Another plan is 
to lay a thin coat of cement on the face of the mould, 
forming the desigTi with small marble chips by hand, by 
pressing the marble into the cement as desired. When 
it is firm, it is backed up with the ordinary stuff, and 
when set, they are ground and polished. 

Concrete Mosaic Laid "in Situ.'' — Pavements for 
halls, passages, shops, landings, &c., are also done in situ. 
A rough concrete foundation is first laid fair to falls 
and levels within 14 i^ich of the finished surface line. 
This % inch space is to receive the plastic marble mo- 
saic. The main or centre part is generally done first 
and the border last. This allows a walking space or 
bearing for boards, laid from side to side to work on 
when laying the centre. A plank sufficiently strong to 
keep one or two crossboards from touching the work is 



HOW TO USE THEM 335 

laid along each side. On the side planks the crossboards 
are laid, and moved about when required. The width of 
the border is marked on the floor, and wood screed rules 
laid level to the marks to form a fair joint line for the 
border, also as a screed when floating the centre part. 
The screed rules are generally fixed with a gauge plaster, 
which is quicker than fixing on gauged cement. After 
the centre is laid, the plaster should be carefully swept 
off, and the concrete well wetted before the border is laid. 
The marble and cement is gauged in the proportion of 2 
of marble to 1 of cement, and laid flush with screeds, 
laying and beating it in position with a long wood hand- 
float. The surface is ruled in from screed to screed with 
a straight-edge. The surface is then ironed with a lay- 
ing trowel until it is smooth and fair. If the marble 
does not show, or is not regular, or is insufficient, the 
bare parts are filled in with marble by hand. When 
marble is scarce, the % inch of the top surface is laid in 
two coats, the first being composed of cement and a 
cheaper aggregate, such as broken stone, tiles, &c., and 
gauged in the same proportion as the upper or marble 
coat. It is laid about i^ inch thick, and when it is firm, 
but not set, the marble coat is laid as before directed. 
The first coat saves the marble, and being firm, tends to 
keep the marble in the upper coat from sinking. The 
top coat is sometimes sprinkled over with fine marble 
chips by hand or through a fine sieve, then pressed into 
the surface and ironed with a laying trowel. Before 
ironing the surface, care should be taken that the chips 
are equally distributed, also that their flat surfaces are 
uppermost, and that the matrix and chips are perfectly 
solid and free from ridges and holes. After the centre 
is laid and the screeds removed, the border is laid in a 



336 CEMENTS AND CONCRETES 

similar way. If there are two or more colors or forms in 
the border, the divisions are formed with narrovv screed 
rules, and arranged so that as many as practicable can 
be laid at the same time. This allows the various parts 
to set at one time, and saves waiting for each separate 
part to set. The screed rules for circular work or angles 
are formed with strong gauged plaster and then oiled. 

The marble chips are either broken by hand or in a 
stone-breaking machine. The chips vary in size from 
1-10 to 1/4 inch. The best colors for borders are a black 
matrix with white marble or spar chips, or a white 
matrix with black marble chips. The white matrix is 
obtained by mixing the marble dust (produced when 
breaking the marble into chips) with a light colored 
Portland cement. The centres can be made in various 
tints, but the most general is a warm red, which is ob- 
tained by mixing the cement with red oxide. Cement 
colored with red oxide should be laid first, as it is liable 
to stain other parts of a lighter color. When the centre 
and border are laid, the floor is left until the whole is 
perfectly set and hard, and it is then fit to polish. This 
is done by means of a stone polisher, water and marble 
dust, or fine slag powder. The stone polisher is a piece 
of hard stone from 8 to 12 inches square, and about 3 
inches thick, into which an iron ring is inserted and se- 
cured with lead. A wooden handle from 4 to 6 feet long, 
with an iron hook at one end, is inserted into the ring, 
so that the handle is firm on the stone, yet has sufficient 
play to be moved freely backwards and forwards. The 
polishing should not be attempted until the stuff is thor- 
oughly set, because the polishing will destroy the face 
of the cement, and cause a vast amount of extra labor in 
grinding the surface down until free from holes. Small 



HOW TO USE THEM 337 

parts of the gauged stuff should be set aside as tests for 
determining when the stuff is set. Concrete mosaic, 
where economy is desirable, will make a strong, durable, 
and waterproof floor, and an excellent substitute for 
higher class mosaics. 

A Bulletin (No. 235), prepared by P. S. Wormley for 
the U. S. government on cement, mortar, and concrete, 
from which I quote at length, contains some excellent in- 
formation and instructions on the preparation and the 
use of the above materials. This bulletin is intended for 
free distribution and may be obtained by making appli- 
cation to the U. S. Department of Agriculture, Wash- 
ington, D. C. 

Storing Cement. — In storing cement care must be ex- 
ercised to insure its being kept dry. When no house or 
shed is available for the purpose, a rough platform may 
be erected clear of the ground, on which the cement may 
be placed and so covered as to exclude water. When 
properly protected, it often improves with age. Cement 
is shipped in barrels or bags, the size and weight of 
which usually are given. 

Cement Mortar. — Cement mortar is an intimate mix- 
ture of cement and sand mixed with sufficient water to 
produce a plastic mass. The amount of water will vary 
according to the proportion and condition of the sand, 
and had best be determined independently in each case. 
Sand is used both for the sake of economy and to avoid 
cracks due to shrinkage of cement in setting. Where 
great strength is required, there should be at least suffi- 
cient cement to fill the voids or air spaces in the sand, 
and a slight excess is preferable in order to compensate 
for any uneven distribution in mixing. Common propor- 
tions for Portland cement mortar are 3 parts sand to 1 



338 CEMENTS AND CONCRETES 

of cement, and for natural cement mortar, 2 parts sand 
to 1 of cement. Unless otherwise stated, materials for 
mortar or concrete are considered to be proportioned by 
volume, tbe cement being slightly shaken in the measure 
used. 

A ''lean" mortar is one having only a small propor- 
tion of cement, while a "rich" mixture is one with a 
large proportion of cement. "Neat" cement is pure 
cement, or that with no admixture of sand. The term 
"aggregate" is used to designate the coarse materials en- 
tering into concrete — usually gravel or crushed rock. 
The proportion in which the three elements enter into 
the mixture is usually expressed by three figTires sepa- 
rated by dashes — as, for instance, 1-2-5, meaning 1 part 
cement, 2 parts sand, and 5 parts aggregate. In the 
great majority of cases cement mortar is subjected only 
to compression, and for this reason it would seem nat- 
ural that, in testing it, to determine its compressive 
strength. The tensile strength of cement mortar, how- 
ever, is usually determined, and from this its resistance 
to compression irsly be assumed to be from 8 to 12 times 
greater. A direct determination of the compressive 
strength is a less simple operation, for Avhich reason the 
tensile test is in most cases accepted as indicating the 
strength of the cement. 

Mixing. — In mixing cement mortar it is best to use a 
platform of convenient size or a shallow box. First, de- 
posit the requisite amount of sand in a uniform layer, 
and on top of this spread the cement. These should be 
mixed dry with shovels or hoes, until the whole mass ex- 
hibits a uniform color. Next, form a crater of the dry 
mixture, and into this pour nearly the entire quantity of 
water required for the batch. Work the dry material 



HOW TO USE THEM 339 

from the outside toward the centre, until all the water 
is taken up, then turn rapidly with shovels, adding water 
at the same time by sprinkling until the desired consist- 
ency is attained. It is frequently specified that the mor- 
tar shall be turned a certain number of times^ but a bet- 
ter practice for securing a uniform mixture is to watch 
the operation and judge by the eye when the mixing has 
been carried far enough. In brick masonry the mis- 
take is frequently made of mixing the mortar very wet 
and relying upon the bricks to absorb the excess of 
water. It is better, however, to wet the brick thoroughly 
and use a stiff mortar. 

Grout. — The term ''grout" is applied to mortar mixed 
with an excess of water, which gives about the consist- 
ency of cream. This material is often used to fill the 
voids in stone-masonry, and in brick work the inner por- 
tions of walls are frequently laid dry and grouted. The 
practice in either case is to be condemned, except where 
the conditions are unusual, as cement used in this way 
will never develop its full strength. 

Lime and Cement Mortar. — L. G. Sabin finds that in 
Portland cement mortar containing three parts sand to 
1 of cement, 10 per cent, of the cement may be replaced 
by lime in the form of paste without diminishing the 
strength of the mortar, and at the same time rendering it 
more plastic. In the case of natural cement mortar, lime 
may be added to the extent of 20 to 25 per cent, of the 
cement with good results. The increased plasticity due 
to the addition of lime much facilitates the operation of 
laying bricks, and has caused lime and cement mortar to 
be largely used. 

Cement Mortar for Plastering. — In plastering with 
cement, a few precautions must be observed to insure 



340 CEMENTS AND CONCRETES 

good and permanent results. The surface to receive the 
plaster should be rough, perfectly clean, and well satu- 
rated with water. A mortar very rich in cement is 
rather a drawback than otherwise on account of shrink- 
age cracks, which frequently appear. The mortar, con- 
sisting of two or three parts sand to one of cement, 
should be mixed with as little water as possible and well 
worked to produce plasticity. It is essential that the 
plaster be kept moist until it has thoroughly hardened. 

Materials for Making Concrete Sand. — In securing 
sand for mixing mortar or concrete, if it is possible to 
select from several varieties, that sand should be chosen 
which is composed of sharp, angular grains, varying in 
size from coarse to fine. Such sand is, however, not 
always obtainable, nor is it essential for good work. Any 
coarse-grained sand which is fairly clean will answer 
the purpose. If gravel, sticks, or leaves be present they 
should be removed by screening. The voids in sand vary 
from 30 to -iO per cent., according to the variation in 
size of grains. A sand Avith different-sized grains is to 
be preferred, because less cement is required to fill the 
voids. By mixing coarse and fine sand it is possible to 
reduce the voids considerably. 

It is customary to use the terms ''river sand," "sea 
sand," or "pit sand," according to the source of the 
supply. River sand as a rule has rounded grains, but 
unless it contains an excess of clay or other impuinties, it 
is suitable for general purposes. When river sand is of 
a light color and fine-grained it answers well for plaster- 
ing. 

Sea sand may contain the salts found in the ocean. 
The tendency of these salts to attract moisture makes it 



HOW TO USE THEM 341 

advisable to wash sea sand before using it for plastering 
or other work which is to be kept perfectly dry. 

Pit sand for the most part will be found to have 
sharp, angular grains, which make it excellent for mor- 
tar or concrete work. Where clay appears in pockets it 
is necessary either to remove it, or else see that it is 
thoroughly mixed with the sand. The presence of clay in 
excess frequently makes it necessary to wash pit sand 
before it is suitable for use. 

The results of tests made in this laboratory would in- 
dicate that the presence of clay, even in considerable 
amounts, is a decided benefit to ' ' lean ' ' mortars, whereas 
it does not appreciably affect the strength of a rich 
mixture. 

Gravel. — It is important that gravel for use in con- 
crete should be clean, in order that the cement may prop- 
erly adhere to it, and form a strong and compact mass. 
As with sand, it is well to have the pieces vary in size, 
thereby reducing the voids to be filled with mortar. The 
voids in general range from 35 to 40 per cent. 

Crushed Stone.— The best stone for concrete work con- 
sists of angular pieces, varying in size and having a 
clean, rough surface. Some form of strong and durable 
rock is to be preferred, such as limestone, trap, or gran- 
ite. The total output of the crusher should be used be- 
low a maximum size, depending upon the nature of the 
work in hand. All material under % i^ch will act as so 
much sand and should be considered as such in propor- 
tioning the mixture. Precautions must be taken to in- 
sure a uniform distribution of the smaller pieces of stone, 
otherwise the concrete will have an excess of fine ma- 
terial in seme parts and a deficiency in others. 



342 CEMENTS AND CONCRETES 

Less than 8 per cent, of clay will probably not seri- 
ously impair the strength of the concrete, provided the 
stones are not coated with it, and may even prove a 
benefit in the case of lean mixtures. The voids in crushed 
stone depend upon the shape and variation in size of 
pieces, rarely falling below 40 per cent., unless much 
fine material is present, and in some cases reaching 50 
per cent. A mixture of stone and gravel in equal parts 
makes an excellent aggregate for concrete. 

Stone Vei^sus Gravel. — It would appear from tests that 
crushed stone makes a somewhat stronger concrete than 
gravel, but the latter is very extensively used with uni- 
formly good results. This superiority of stone over 
gravel for concrete work is attributed to the fact that the 
angular pieces of stone interlock more thoroughly than 
do the rounded pebbles, and offer a rougher surface to 
the cement. A point in favor of gTavel concrete is that 
it requires less tamping to produce a compact mass than 
in the case of crushed stone. Then, too, the proportion 
of voids in stone being usually greater than in gravel, 
means a slight increase in the cost of concrete. 

Cinders. — Cinders concrete is frequently used in con- 
nection with expanded metal and other forms of rein- 
forcement for floor construction, and for this purpose it 
is well adapted on account of its light weight. Its poros- 
ity makes it a poor conductor of heat and permits the 
driving of nails. Onlv hard and thoroughlv burned cin- 
ders should be used, and the concrete must be mixed 
quite soft so as to require but little tamping and to avoid 
crushing the cinders. Cinder concrete is much weaker, 
both in tension and compression, than stone or gravel 
concrete, and for this reason admits only of light rein- 
forcement. 



' HOW TO USE THEM 343 

Concrete. — General Discussion: Cement concrete is 
the product resulting from an intimate mixture of 
cement mortar with an aggregate of crushed stone, 
gravel, or similar material. The aggregate is crushed or 
screened to the proper size as determined from the char- 
acter of the work. In foundation work, stone or gravel 
3 inches in size may be used to advantage, whereas in the 
case of moulded articles of small sectional area, such as 
fence posts, hollow building blocks, &c., it is best to use 
only such material as will pass a % inch screen. An 
ideal concrete, from the standpoint of economy, would 
be that in which all voids in the aggregate were com- 
pletely filled with sand, and all the voids in the sand 
completely filled with cement, without any excess. Un- 
der these conditions there would be a thoroughly com- 
pact mass and no waste of materials. 

It is a simple matter to determine the voids in sand 
and also in the aggregate, but in mixing concrete the 
proportions vary a great deal, depending in each case 
upon the nature of the work and the strength desired. 
For example, in the construction of beams and floor pan- 
els, where maximum strength with minimum weight is 
desired, a rich concrete should be used, whereas in mas- 
sive foundation work, in which bulk or weight is the 
controlling factor, economy would point to a lean mix- 
ture. When good stone or gravel is used, the strength of 
the concrete depends upon the strength of the mortar em- 
ployed in the mixing and the proportion of mortar to 
aggregate. For a given mortar the concrete will be 
strongest when only enough mortar is used to fill the 
voids in the aggregate, less strength being obtained by 
using either greater or less proportion. In practice it is 



344 CEMENTS AND CONCEETES 

usual to add a slight excess of mortar over that required 
to fill the voids in the aggregate. 

It is more accurate to measure cement by weight un- 
less the unit employed be the barrel or sack, because 
when taken from the original package and measured in 
bulk there is a chance of error due to the amount of 
shaking the cement receives. As it is less convenient, 
however, to weigh the cement, it is more usual to 
measure it by volume, but for the reasons stated this 
should be done with care. 

Proportioning Materials. — For an accurate determina- 
tion of the best and most economical proportions where 
maximum strength is required, it is well to proceed in 
the following way: First, proportion the cement and 
sand so that the cement paste will be 100 per cent, in ex- 
cess of the voids in sand; next, determine the voids in 
the aggregate and allow sufficient mortar to fill all voids, 
with an excess of 10 per cent. 

To determine roughly the voids in gravel or crushed 
stone prepare a water-tight box of convenient size and 
fill with the material to be tested, shake well and smooth 
off even with the top. Into this pour water until it rises 
flush with the surface. The volume of water added, 
divided by the volume of the box, measured in the same 
units, represents the proportion of voids. The propor- 
tion of voids in sand may be more accurately determined 
by subtracting the weight of a cubic foot of packed sand 
from 165, the weight of a cubic foot of quartz, and divid- 
ing the difference by 165 degrees. 

The following will serve as an example of proportion- 
ing materials : Assume voids in packed sand to measure 
38 per cent., and voids in packed stone to measure 48 
per cent. Cement paste required per cubic foot of sand, 



HOW TO USE THEM 345 

0.38 and 1-10 equals 0.42 cubic foot, approximately. By 
trial, 1 cubic foot of loose cement, lightly shaken, makes 

0.85 cubic foot of cement paste, and requires ^^ or 
2 cubic feet of sand, approximately, producing an 
amount of mortar equal to 0.85 and 2 (1-0.38) equals 
2.09 cubic feet. Mortar required per cubic foot of stone 
equals 0.48, and 1-10x0.48 equals 0.528 cubic foot. There- 
fore 2.09 cubic feet mortar will require ^ equals 
4 cubic feet of stone, approximately. The proportions 
are therefore 1 part cement, 2 parts sand, 4 parts stone. 
Although such a determination is usually considered un- 
necessary in practical work, it may be of sufficient inter- 
est to justify giving it. 

For general use the following mixtures are recom- 
mended : 1 cement, 2 sand, 4 aggregate, for very strong 
and impervious; 1 cement, 2% sand, 5 aggregate, for 
ordinary work requiring moderate strength ; 1 cement, 3 
sand, 6 aggregate, for work where strength is of minor 
importance. 

Aggregate Containing Fine Material. — In the case of 
gravel containing sand, or crushed stone from which the 
small articles have not been removed by screening, the 
amount of such fine sand or fine stone should be deter- 
mined and due allowance made for it in proportioning 
the mortar. 

When mixing an aggregate containing small particles 
with mortar, and in reality we have a mortar containing 
a larger proportion of sand than was present before the 
aggregate was incorporated. It is evident, then, that in 
such cases the quality of richness of the mortar should 
depend upon the proportion of fine material in the ag- 
gregate. 



346 CEMENTS AND CONCBETES 

For example, suppose that 1 cubic foot of gravel con- 
tains 0.1 cubic foot of sand, and that the voids in gravel 
with sand screened out measure 40 per cent. For gen- 
eral purposes this would suggest a 1-2-5 mixture, but 
since each cubic foot contains 0.1 cubic foot sand, 5 
cubic feet gravel will contain 0.5 cubic foot sand, and 
the proportions should be changed to 1 part cement, 1% 
parts sand, 5 parts gravel. 

Mechanical Mixers. — It has been demonstrated that 
concrete can be mixed by machinery as well, if not bet- 
ter, than by hand. Moreover, if large quantities of con- 
crete are required, a mechanical mixer introduces marked 
economy in the cost of construction. None of the various 
forms of mechanical mixers will be described here, since 
concrete in small quantities, as would be used on the 
farm, is more economically mixed by hand. 

Mixing hy Hand. — In mixing by hand a platform is 
constructed as near the work as is practicable, the sand 
and aggregate being dumped in piles at the side. If the 
work is to be continuous, this platform should be of suf- 
ficient size to accommodate two batches, so that one batch 
can be mixed as the other is being deposited. The ce- 
ment must be kept under cover and well protected from 
moisture. A convenient way of measuring the materials 
is by means of a bottomless box or frame made to hold 
the exact quantities needed for a batch. 

A very common and satisfactory method of mixing 
concrete is as follows : First measure the sand and ce- 
ment required for a batch and mix these into mortar as 
described on page 5. Spread out this mortar in a thin 
layer and on top of it spread the aggregate, which has 
been previously measured and well wetted. The mixing 
is done by turning with shovels three or more times, as 



HOW TO USE THEM 347 

may be found necessary to produce a thoroughly uni- 
form mixture, water being added if necessary to give 
the proper consistency. The mixers, two or four in num- 
ber, according to the size of the batch, face each other 
and shovel to right and left, forming two piles, after 
which the material is turned back into a pile at the cen- 
tre. By giving the shovel a slight twist, the material is 
scattered in leaving it and the efficiency of the mixing 
is much increased. 

Consistency of Concrete. — A dry mixture, from which 
water can be brought to the surface only by vigorous 
tamping, is probably the strongest, but for the sake of 
economy, and to insure a dense concrete well filling the 
moulds a moderately soft mixture is recommended for 
ordinary purposes. Where the pieces to be moulded are 
thin, and where small reinforcing metal rods are placed 
close together or near the surface, a rather wet mixture 
may be necessary to insure the moulds being well filled. 

Use of Quick-Setting Cement. — In the manufacture 
of such articles as pipe, fence posts, and hollow blocks, 
a rather large proportion of quick-setting cement is 
sometimes used, the object being to reduce the weight 
and consequent freight charges by means of a strong 
mixture, as well as to make the concrete impervious to 
water. The use of a quick-setting cement permits the 
moulds to be removed sooner than would be possible with 
a slow-setting cement, thus reducing the number of 
moulds necessary for a given output. Quick-setting ce- 
ments are not recommended for such purposes, however, 
as they are usually inferior to those which set slowly. 

Coloring Cement Work. — In coloring cement work the 
best results are obtained by the use of mineral pig- 
ment. The coloring matter, in proportions depending 



348 CEMENTS AND CONCRETES 

upon the desired shade, should be thoroughly mixed with 
the dry cement before making the mortar. By prepar- 
ing small specimens of the mortar and noting the color 
after drying, the proper proportions may be determined. 

For gray or black, use lampblack. 

For yellow or buff, use yellow ochre. 

For brown, use umber. 

For red, use Venetian red. 

For blue, use ultramarine. 

Depositing Concrete. — Concrete should be deposited 
in layers of from 4 to 8 inches and thoroughly tamped 
before it begins to harden. The tamping required will 
depend upon the consistency of the mixture. If mixed 
very dry it must be vigorously rammed to produce a 
dense mass, but as the proportion of water increases less 
tamping will be found necessary. Concrete should not 
be dumped in place from a height of more than 4 feet, 
unless it is again mixed at the bottom. A wooden in- 
cline may be used for greater heights. Rammers for 
ordinary concrete work should weigh from 20 to 30 
pounds and have a face not exceeding 6 inches square. 
A smaller face than this is often desirable, but a larger 
one will be less effective in consolidating the mass. In 
cramped situations special forms must be employed to 
suit the particular conditions. When a thickness of 
more than one layer is required, as in foundation work, 
two or more layers may be worked at the same time, each 
layer slightly in advance of the one next above it and 
ail being allowed to set together. At the end of a day 
there is usually left a layer partially completed which 
must be finished the next day. This layer should not be 
beveled off, but the last batch of concrete should be 
tamped behind a vertical board forming a step. 



HOW TO USE TKEM 349 

To avoid introducing a plane of weakness where f resli 
concrete is deposited upon that which has already set, 
certain precautions have to be observed. The surface of 
the old work should be clean and wet before fresh ma- 
terial is put on, a thin coat of neat cement grout being 
sometimes employed to insure a good bond. The sur- 
face of the concrete to receive an additional layer must 
not be finished off smoothly, but should offer a rough 
surface to bond with the next layer. This may be done 
by roughing the surface while soft with pick and shovel, 
or the concrete may be so rammed as to present a rough 
and uneven surface. Wooden blocks or scantling are 
sometimes embedded several inches in the work and re- 
moved before the concrete hardens, thus forming holes 
or grooves to be filled by the next layer. 

Retempering. — As stated before, it is important that 
concrete be tamped in place before it begins to harden, 
and for this reason it is proper to mix only so much at a 
time as is required for immediate use. The retempering 
of concrete which has begun to set is a point over which 
there is much controversy. From tests made in this 
laboratory it would appear that such concrete suffers but 
little loss of strength if thoroughly mixed with sufficient 
water to restore normal consistence. 

The time required for concrete to set depends upon 
the character of the cement, upon the amount and tem- 
perature of the water used in mixing, and upon the 
temperature of the air. Concrete mixed dry sets more 
quickly than if mixed wet, and the time required for 
setting decreases as the temperature of the water rises. 
Warm air also hastens the setting. 

Concrete Exposed to Sea-Water. — Portland cement 
concrete is well adapted for work exposed to sea-water, 



350 CEMENTS AND CONCRETES 

but when used for this purpose it should be mixed with 
fresh water. The concrete must be practically imper- 
vious, at least on the surfaces, and to accomplish this 
purpose the materials should be carefully proportioned 
and thoroughly mixed. It is also of great importance 
that the concrete be well compacted by tamping, par- 
ticularly on exposed surfaces. 

Concrete Work in Freezing Weather. — Although it is 
advisable under ordinary conditions to discontinue ce- 
ment work in freezing weather, Portland cement may be 
used without serious difficulty by taking a few simple 
precautions. As little water as possible should be used 
in mixing, to hasten the setting of the concrete. To 
prevent freezing, hot water is frequently used in mixing 
mortar or concrete, and with the same object in view salt 
is added in amounts depending upon the degree of cold. 
A common practice is to add 1 pound of salt to 18 gal- 
lons of water, with the addition of 1 oz. of salt for each 
degree below 32° F. Either of the above methods will 
give good results, but it should be remembered that the 
addition of salt often produces efflorescence. It seems 
to be a fairly well-established fact that concrete de- 
posited in freezing weather will ultimately develop full 
strength, showing no injury due to the low temperature. 

Rubble Concrete. — In massive concrete work consider- 
able economy may often be introduced by the use of 
large stones in the body of the work, but only in heavy 
foundations, retaining walls, and similar structures 
should this form of construction be permitted. In plac- 
ing these large stones in the work the greatest care must 
be exercised to insure each being well bedded, and the 
concrete must be thoroughly tamped around them. Each 



HOW TO USE THEM 



351 



stone should be at least 4 inches from its neighbor and 
an equal distance from the face of the work. 

To Face Concrete. — A coating of mortar one-half 
inch in thickness is frequently placed next the form to 
prevent the stone or gravel from showing and to give 
a smooth and impervious surface. If in preparing this 
mortar finely crushed stone is used instead of sand, thf» 







•Sheet-metal plate used in facing concrete, 
NO, 6. 



work will more nearly resemble natural stone. A 
common method employed in facing concrete is to pro- 
vide a piece of thin sheet metal of convenient length 
and about 8 to 10 inches wide. To this pieces of angle 
iron are riveted, so that when placed next to the mould 
a narrow space is formed in which the cement mortar is 
placed after the concrete has been deposited behind it. 
(No. 6.) The metal plate is then withdrawn and the 



852 CEMENTS AND CONCRETES 

concrete well tamped. The concrete and facing mor- 
tar must be put in at the same time so that they will 
set together. If the concrete is fairly rich, a smooth 
surface can usually be produced without a facing of 
mortar by working a spade up and down between the 
concrete and inner face of the mould, thus forcing the 
larger pieces of the aggregate back from the surface. 

Wood for Forms. — Lumber used in making forms for 
concrete should be dressed on one side and both edges. 
The expansion and distortion of the wood due to the 
absorption of water from the concrete frequently make 
it difficult to produce an even surface on the work, and 
unless the forms are accurately fitted together more or 
less water will find its way out through the cracks, 
carrying some of the cement with it. A method some- 
times adopted to minimize the effect of expansion is to 
bevel one edge of each board, allowing this edge to 
crush against the square edge of the adjacent board 
when expansion takes place. In the case of a wooden 
core or inside mold, expansion must always be taken into 
consideration, for if neglected it may cause cracks or 
complete rupture of the concrete. Sharp edges in con- 
Crete are easily chipped and should ba avoided by plac 
ing triangular strips to the corners of moulds. To pre- 
vent cement from sticking to the forms they may be 
given a coating of soft soap or be lined with paper. 
This greatly facilitates their removal and enables them 
to be used again with but little scraping. A wire brush 
answers best for cleaning the forms. 

Concrete Sidewalks. — A useful and comparatively 
simple application of concrete is in the construction of 
sidewalks, for which purpose it has been ^ised with 
marked success for a number of years. 



HOW TO USE THEM 353 

Excavation and Preparation of Subgrade. — The 
ground is excavated to subgrade and well consolidated 
by ramming to prepare it for the subfoundation of 
stone, gravel or cinders. The depth of excavation will 
depend upon the climate and nature of the ground, 
being deeper in localities where heavy frosts occur or 
where the ground is soft than in climates where there 
are no frosts. In the former case the excavation should 
be carried to a depth of 12 inches, whereas in the latter 
from 4 to 6 inches will be sufficient. No roots of trees 
should be left above the subgrade. 

The Subfoundation. — The foundation consists of a 
layer of loose material, such as broken stone, gravel, 
or cinders, spread over the subgrade and well tamped to 
secure a firm base for the main foundation of concrete 
which is placed on top. It is most important that the 
subfoundation be well drained to prevent the accumula- 
tion of water, which, upon freezing, would lift and crack 
the walk. For this purpose it is well to provide drain 
tile at suitable points to carry off any water which may 
collect under the concrete. An average thickness for 
subfoundation is 4 to 6 inches, although in warm cli- 
mates, if the ground is firm and well drained, the sub- 
foundation may only be 2 to 3 inches thick or omitted 
altogether. 

The Foundation. — The foundation consists of a layer 
of concrete deposited on the subfoundation and carry- 
ing a surface layer or wearing coat of cement mortar. If 
the ground is firm and the subfoundation well rammed 
in place and properly drained, great strength will not be 
required of the concrete, which may, in such cases, be 
mixed in about the proportions 1-3-6, and a depth of only 
3 to 4 inches will be required. Portland cement should 



354 CEMENTS AND CONCRETES 

be used and stone or gravel under 1 inch in size, the con- 
crete being mixed of medium consistency, so that 
moisture will show on the surface without excessive 
tamping. 

The Top Dressing or Wearing Surface. — To give a 
neat appearance to the finished walk, a top dressing of 
cement mortar is spread over the concrete, well worked 
in, and brought to a perfectly smooth surface with 
straightedge and float. This mortar should be mixed 
in the proportion 1 part cement to 2 parts sand, sharp 
coarse sand or screenings below one-fourth inch of some 
hard, tough rock being used. The practice of making 
the concrete of natural cement and the wearing surface 
of Portland is not to be commended, owing to a tendency 
for the two to separate. 

Details of Construction. — A cord stretched between 
stakes will serve as a guide in excavating, after which 
the bottom of the trench is well consolidated by ram- 
ming; any loose material below subgrade is then spread 
over the bottom of the trench to the desired thickness 
and thoroughly compacted. Next, stakes are driven 
along the sides of the walk; spaced 4 to 6 feet apart, 
and their tops made even with the finished surface of 
the walk, which should have a transverse slope 
of one-fourth inch to the foot for drainage. Wooden 
strips at least iy2 inches thick and of a suitable depth 
are nailed to these stakes to serve as a mould to concrete. 
By carefully adjusting these strips to the exact height of 
the stakes they may be used as guides for the straight- 
edge in levelling off the concrete and wearing surface. 
The subfoundation is well sprinkled to receive the con- 
crete, which is deposited in the usual manner, well 
tamped behind a board set vertically across the trench, 



HOW TO USE THEM 



355 



and levelled off with a straightedge as shown in Fig. 7, 
leaving one-half to 1 inch for the wearing surface. 
Three-eighths inch sand joints are provided at intervals 
of 6 to 8 feet to prevent expansion cracks, or, in case of 
settlement, to confine the cracks to these joints. This is 
dene either by depositing the concrete in sections, or by 
dividing it into such sections with a spade when soft and 
filling the joints with sand. The location of each joint 
is marked on a wooden frame for future reference. 






. .r"''"!!'!!, 

, ' •'"•>iV.HIiifii 













..:.,.^•"m■"!!ll^!K;.>, 



'■".vH'io.'i':' - L- .... '*^- ■ - 

:DetallB of concrete walk constractlon. 
NO. 7. 

Care must be exercised to prevent sand or any other 
material from being dropped on the concrete, and thus 
preventing a proper union with the wearing surface. No 
section should be left partially completed to be finished 
with the next batch or left until the next day. Any con- 
crete left after the completion of a section should be 
mixed with the next batch. 

It is of the utmost importance to follow up closely the 
concrete work with the top dressing in order that the 



356 CEMENTS AND CONCRETES 

two may set together. This top dressing should be 
worked well over the concrete with a trowel, and levelled 
with a straightedge (No. 7) to secure an even surface. 
Upon the thoroughness of this operation often depends 
the success or failure of the walk, since a good bond be- 
tween the wearing surface and concrete base is absolute- 
ly essential. The mortar should be mixed rather stiff. 
As soon as the film of water begins to leave the surface, 
a wooden float is used, followed up by a plasterer's 
trowel, the operation being similar to that of plastering 
a wall. The floating, though necessary to give a smooth 
surface, will, if continued too long, bring a thin layer of 
neat cement to the surface and probably cause the walk 
to crack. 




Jointer used in dividing walli 
into sections. 

NO. 8. 

The surface is now divided into sections by cutting en- 
tirely through, exactly over the joints in the concrete. 
This is done with a trowel guided by a straightedge, 
after which the edges are rounded oft' with a special tool 
called a jointer, having a thin shallow tongue (No. 8). 
These sections may be subdivided in any manner desired 
for the sake of appearance. 

A special tool called an edger (No. 9) is run round the 
outside of the walk next to the mould, giving it a neat 
rounded edge. A toothed roller (No. 10) having small 



HOW TO USE THEM 



357 



projections on its face is frequently used to produce 
slight indentations on the surface, adding somewhat to 




Tool used in rounding edges. 
NO. 9. 

the appearance of the walk. The completed work must 
be protected from the sun and kept moist by sprinkling 




Roller used in finishing surl^ce 
NO. 10. 

for several days. In freezing weather the same precau- 
tions should be taken as in other classes of eoncrejte 
work. 



358 CEMENTS AXD CONCRETES 

Concrete Basement Floors. — Basement floors in dwell- 
ing houses as a rule require only a moderate degree of 
strength, although in cases of very wet basements, where 
water pressure from beneath has to be resisted, greater 
strength is required than would otherwise be necessary. 
The subfoimdation should be well drained, sometimes re- 
quiring the use of tile for carrying off the Avater. The 
rules given for constructing concrete sidewalks apply 
equally well to basement floors. The thickness of the 
concrete foundation is usuallv from 3 to 5 inches, ac- 
cording to the strength desired, and for average work a 
1-3-6 mixture is sufficiently rich. Expansion joints are 
frec^uently omitted, since the temperature variation is 
less than in outside work, but since this omission fre- 
quently gives rise to unsightly cracks, their use is recom- 
mended in all cases. It will usuallv be sufficient to 
divide a room of moderate size into four equal sections, 
separated by % inch sand joints. The floor should be 
given a slight slope toward the center or one corner, with 
provision at the lowest point for carrying off any water 
that maA^ accumulate. 

Concrete StahJe Floors aneJ Driveivays. — Concrete 
stable floors and clrivewaA's are constructed in the same 
general Avay as basement floors and sicleAvalks, but AA'ith 
a thicker foundation, on account of the greater strength 
required. The foundation may Avell be 6 inches thick, 
:with a 10 inch wearing surface. An objection often 
sometimes raised asainst concrete driA^ewaA^s is that they 
become slippery Avhen AA'et; but this fault is in a great 
measure oA^rccme by diA'iding the wearing surface into 
small squares about -1 inches on the side, by means of tri- 
angular grooves % of an inch deep. This gives a very 



HOW TO USE THEM 



359 



neat appearance and furnishes a good foothold for 
horses. 

Concrete Steps. — Concrete may be advantageously 
used in the construction of steps, particularly in damp 
places, such as areaways and cellars of houses, and in 
the open, where the ground is terraced, concrete steps 
and walks can be made exceedingly attractive. Where 
the "ground is firm it may be cut away as nearly as pos- 
sible in the form of steps, with each step left two or 
three inches below its finished level. The steps are 
formed, beginning at the top, by depositing the con- 




Reinforced concrete steos. 

NO. 11. 



Crete behind vertical boards so placed as to give the nec- 
essary thickness to the risers and projecting high enough 
to serve as a guide in leveling off the tread. Such steps 
may be reinforced where greater strength is desired or 
where there is danger of cracking, due to the settlement 
of the ground. 

Where the nature of the ground will not admit of its 
being cut away in the form of steps, the risers are 



360 CEMENTS AND CONCRETES 

molded between two vertical forms. The front one may 
be a smooth board, but the other should be a piece of 
thin sheet metal, which is more easily removed after tke 
earth has been tamped in behind rt. A simple method 
of reinforcing steps is to place a 14 i^ch steel rod in each 
comer, and thread these with y^ inch rods bent to the 
shape of the steps, as showm in No. 11, the latter being 
placed about 2 feet apart. For this class of work a rich 
Portland cement concrete is recommended, with the use 
of stone or gravel under % inch in size. Steps may be 
given a % inch wearing surface of cement mortar mixed 
in the proportion of 1 part cement to 2 parts sand. This 
system, as well as many others, is well adapted for stair- 
ways in houses. 

Reinforced Concrete Fence Posts. — Comparison of dif- 
ferent Post Materials: There is a constantly increasing 
demand for some form of fence posts which is not sub- 
ject to decay. The life of wooden posts is very limited, 
and the scarcity of suitable timber in many localities 
has made it imperative to find a substitute. A fence 
post, to prove thoroughly satisfactory, must fulfil three 
conditions: (1) It must be obtainable cost; (2) it must 
possess sufficient strength to meet the demands of gen- 
eral farm use; (3) it must not be subject to decay, and 
must be able to withstand successfully the effects of 
water, frost and fire. Although iron posts of various 
designs are frequently used for ornamental purposes, 
their adoption for general farm use is prohibited by their 
excessive cost. Then, too, iron posts exposed to the 
weather are subject to corrosion, to prevent which neces- 
sitates repainting from time to time, and this item will 
entail considerable expense in cases where a large num- 
ber of posts are to be used. 



HOW TO USE THEM 361 

At the present time the material which seems most 
nearly to meet these requirements is reinforced con- 
crete. The idea of constructing fence posts of concrete 
reinforced with iron or steel is by no means a new one, 
but, on the contrary, such posts have been experimented 
with for years, and a great number of patents have been 
issued covering many of the possible forms of reinforce- 
ment. It is frequently stated that a reinforced con- 
crete post can be made and put in the ground for the 
same price as a wooden post. Of course this will de- 
pend in any locality upon the relative value of wood and 
the various materials which go to make up the concrete 
post, but in the great majority of cases wood will prove 
the cheaper material in regard to first cost. On the 
other hand, a concrete post will last indefinitely, its 
strength increasing with age, whereas the wooden post 
must be replaced at short intervals, probably making it 
more expensive in the long run. 

In regard to strength, it must be borne in mind that 
it is not practicable to make concrete fence posts as 
strong as wooden posts of the same size ; but since wooden 
posts, as a rule, are many times stronger than is neces- 
sary, this difference in strength should not condemn the 
use of reinforced concrete for this purpose. Moreover, 
strength in many cases is of little importance, the fence 
being used only as a dividing line, and in such cases 
small concrete posts provide ample strength and present 
a very uniform and neat appearance. In any case, to 
enable concrete posts to withstand the loads they are 
called upon to carry, sufficient strength may be secured 
by means of reinforcement, and where great strength is 
required this may be obtained by using a larger post 
with a greater proportion of metal and well braced, as 



362 CEMENTS AND CONCRETES 

is usual in such cases. In point of durability, concrete 
is unsurpassed by any material of construction. It offers 
a perfect protection to the metal reinforcement and is 
not itself affected by exposure, so that a post constructed 
of concrete reinforced with steel will last indefinitely and 
require no attention in the way of repairs. 

B 6171 for cement. — No form of wooden reinforcement, 
either on the surface or within the post, can be recom- 
mended. If on the surface, the wood will soon decay, 
and if a wooden core is used it will; in all probability, 
swell by the absorption of moisture and crack the post. 
The use of galvanized wire is sometimes advocated, but 
if the post is properly constructed and a good concrete 
used, this precaution against rust will be unnecessary, 
since it has been fully demonstrated by repeated tests 
that concrete protects steel perfectly from rust. If 
plain, smooth wire or rods are used for reinforcement 
they should be bent over at the ends or looped to pre- 
vent slipping in the concrete. Twisted fence wire may 
usually be obtained at a reasonable cost and is very well 
suited for this purpose. Barbed wire has been proposed 
and is sometimes used, although the barbs make it ex- 
tremely difficult to handle. For the sake of economy the 
smallest amount of metal consistent with the desired 
strength must be used, and this requirement makes it 
necessary to place the reinforcement near the surface, 
where its strength is utilized to greatest advantage, with 
only enough concrete on the outside to form a protective 
covering. A reinforcing member in each corner of the 
post is probably the most efficient arrangement. ' 

Concrete for Fence Posts. — The concrete should be 
mixed with Portland cement in about the proportions 
l-2%-5, broken stone or gravel under I/2 inch being used. 



HOW TO USE THEM 



363 



In cases where the aggregate contains pieces smaller 
than 1/4 inch, less sand may be used, and in some cases 
it may be omitted altogether. A mixture of medium con- 
sistency is recommended on the ground that it fills the 
molds better and with less tamping than if mixed quite 
dry. 

Molds for Fence Posts. — Economy points to the use 
of a tapering post, which, fortunately, offers no diffi- 
culties in the way of molding. All things considered, 




^oodea jnold-for making fence posts wltli four tapering sides. 
NO. 12. 



v^Tooden molds will be found most suitable. They can 
easily and quickly be made in any desired form and size. 
Posts may be molded either in a vertical or horizontal 
position, the latter being the simpler and better method. 
If molded vertically a wet mixture is necessary, requir- 
ing a longer time to set, with the' consequent delay in 
removing the molds. No. 12 shows a simple mold, which 
has been used with satisfactory results in this laboratory. 



364 



CEMENTS AND CONCRETES 



This mold has a capacity of four pests, but larger molds 
could easily be made on the same principle. It consists 
of two end pieces, (a) carrying lugs, (b) between which 
are inserted strips (c). The several parts are held to- 
gether with hooks and eyes, as shown in No. 12. To pre- 
vent any bulging of the side strips they are braced, as 
illustrated. Dressed lumber at least 1 inch thick, and 
preferably 1% inches, should be used. In No. 12 the 




.rWooden mold for making fence Dosts with two tapering sides. 

NO. 13. 



post measures 6 by 6 inches at the bottom, 6 by 3 at the 
top, and 7 feet in length, having two parallel sides. If 
it is desired to have the posts square at both ends the 
mold must be arranged as in No. 13. This latter form 
of post is not as strong as the former, but requires less 
concrete in its construction. Great care in tamping is 
necessary to insure the corners of the mold being weU 



HOW TO USE THEM 



365 



filled, and if this detail is not carefully watched, the 
metal, being exposed in places, will be subject to rust. 

Attaching Fence Wires to Posts. — Various devices have 
been Suggested for attaching fence wires to the posts, the 
object of each being to secure a simple and permanent 
fastener or one admitting of easy renewal at any time. 
Probably nothing will answer the purpose better than a 
long staple or bent wire well embedded in the concrete, 
being twisted or bent at the end to prevent extraction. 
Galvanized metal must be used for fasteners, since they 




■Detail showing method of at* 
taching wire to post. 

NO. 14. 



are not protected by the concrete. A piece of small flex- 
ible wire, about two inches in length, threadinc^ the staple 
and twisted several times with a pair of pliers, holds the 
line wire in position. (No. 14.) 

Molding and Curing Posts. — For the proper method of 
mixing concrete see previous pages. It is recommended 
that only so much concrete be mixed at one time as can 
be used before it begins to harden ; but if an unavoidable 
delay prevents the posts being molded until after the 



S66 CEMENTS AND CONCRETES 

concrete has begun to set, it is tliought that a thorough 
regauging with sufficient water to restore normal con- 
sistency will prevent any appreciable loss of strength, 
though the concrete may have been standing one or two 
hours. In using a mold similar to those illustrated in 
Kos. 12 and 13 it is necessary to provide a perfectly 
smooth and even platform of a size depending upon the 
number of posts to be molded. A cement floor if accessi- 
ble may be used to advantage. The molds when in place 
are given a thin coating of soft soap, the platform or 
cement floor, serving as bottom of mold, being treated in 
the same way. About 1^^ inches is spread evenly over 
the bottom and carefully tamped, so as to reduce it to a 
thickness of about 1 inch. A piece of board cut as in 
No. 12 will be found useful in leveling off the concrete to 
the desired thickness before tamping. On top of this 
layer two reinforcing members are placed about 1 inch 
from the sides of the mold. The molds are then filled 
and tamped in thin layers to the level of the other two 
reinforcing members, the fasteners for fence wires being 
inserted during the operation. These reinforcing mem- 
bers are adjusted as were the first two, and the remain- 
ing 1 inch of concrete tamped and leveled off, thus com- 
pleting the post so far as molding is concerned. To avoid 
sharp edges, which are easily chipped, triangular strips 
may be placed in the bottom of mold along the sides, and 
when the molds have been filled and tamped, similar 
strips may be inserted on top. The top edges may be 
beveled with a troAvel or by running an edging tool hav- 
ing a triangular projection on its bottom along the edges. 
Such a tool is shown in No. 15, and can easilv be made 
of wood or metal. It is not necessary to carry the bevel 
below the ground line. 



HOW TO USE THEM 



367 



The ends and sides of the mold may be removed after 
twenty-four hours, but the posts should not be handled 
for at least one week, during which time they must be 
well sprinkled several times daily and protected from sun 
and wind. The intermediate strips may be carefully 
withdrawn at the end of two or three days, but it is bet- 
ter to leave them in place until the posts are removed. 
Although a post may be hard and apparently strong 
when one week old^ it will not attain its full strength in 
that length of time, and must be handled with the utmost 
care to prevent injury. Carelessness in handling green 
posts frequently results in the formation of fine cracks, 
which though unnoticed at the time, give evidence of 
their presence later in the failure of the posts. 




Tool used for beveling edgcsof 
posts. 

NO. 15. 



Posts ishould be allowed to cure for at least sixty days 
before being placed in the ground, and for this purpose 
it is recommended that when moved from the molding 
platform they be placed upon a smooth bed of moist sand 
and protected from the sun until thoroughly cured. Dur- 
ing this period they should receive a thorough drench- 
ing at least once a day. 



368 CE.MEXTS AND COXCRETES 

The life of the molds will depend upon the care with 
which they are handled. A coating of mineral oil or 
shellac may be used instead of soap to prevent the cement 
from sticking to the forms. As soon as the molds are 
removed thev should be cleaned with a wire brush before 
Ibeing used again. 

The cost of reinforced concrete fence posts depends 
in each case upon the cost of labor and materials, and 
must necessarilv varv in different localities. An esti- 
mate in any particular case can be made as follows : One 
cubic yard of concrete will make twenty posts measuring 
6 inches by 6 inches at the bottom, 6 inches by 3 inches 
at the top, and 7 feet long, and if mixed in the propor- 
tions 1-21/2-5. requires approximately: 

1.16 barrels of cement, at $2 $2.32 

0.44 cubic yard of sand, at 75 cts 33 

0.88 cubic yard of gravel, at 75 cts 66 

Materials for 1 cubic yard cement. $3.21 

Concrete for one post 17 

28 feet of 0.16 inch steel wire, at 3 cts a pound 06 

Total cost of concrete and metal for 1 post 23 

To this must be added the cost of mixing concrete, 
molding and handling posts, and the costs of molds, an 
addition Avhich should not in any case exceed 7 cents, 
making a total of 30 cents per post. 

Concrete Building Blocks. — Concrete building blocks, 
or cement blocks, as they are frequently called, are more 
extensively used now than ever before. These blocks 
are molded hollow primarily to reduce their cost, but 
i:his hollow construction serves other useful purposes at 
the same time. The fundamental principles governing 



HOW TO USE THEM 369 

ordinary concrete work, so far as proportioning and 
mixing materials is concerned, apply equally well to the 
manufacture of building blocks, and it should be borne 
in mind that strength and durability can not be obtained 
by the use of any machine unless the cement, sand, and 
aggregate are of good quality, properly proportioned 
and well mixed. The aggregate for blocks of ordinary 
size should be crushed stone or gravel not larger than 
1/2 inch. One of the chief causes of complaint • against 
the concrete building block is its porosity, but this defect 
is in a great measure due to the fact that in an endeavor 
to economize too little cement is frequently used. It is 
not unusual to give the blocks a facing of cement mor- 
tar consisting of about 2 parts sand to 1 of cement, while 
the body of the block is composed of a concrete of suffi- 
cient strength, though not impervious. This outside 
layer of mortar adds practically nothing to the strength 
of the block, and is used simply to give a uniform sur- 
face and to render the face of the wall more clearly im- 
pervious to water. 

It would not be practicable as a rule to attempt the 
manufacture of concrete blocks without one of the manj 
forms of molding machines designed for the purpose, nor 
would it be economical to purchase such a machine un- 
less a sufficient number of blocks were required to justify 
such an outlay. Blocks in almost any desired shape and 
size, with either plain or ornamental faces, may be ob- 
tained on the market, and in the great majority of cases 
it is best to buy them from some reliable firm. Among 
the advantages claimed for hollow concrete block con- 
struction may be mentioned the following : 

(1) Hollow block construction introduces a saving of 
material over brick or stone masonry. 



370 CEMENTS AND CONCRETES 

(2) The cost of laying concrete blocks is less than for 
brick work. This is due to the fact that the blocks, being 
larger, require a much smaller number of joints and 
less mortar, and, being hollow, are of less weight than 
solid brick work. 

(3) A wall constructed of good concrete blocks is as 
strong or stronger than a brick wall of equal thickness. 

(4) Concrete blocks, being easily molded to any de- 
sired form, will prove to be a far more economical build- 
ing material than stone, which has to be dressed to 
shape. 

(5) Experience has proved concrete to be a most ex- 
cellent fire resisting material. 

(6) Concrete blocks, being hollow, tend to prevent 
sudden changes of temperature within a house, making 
it cool in summer and easily heated in winter. 

(7) The hollow spaces provide an easy means for 
running pipes and electric wires. These spaces may also 
be used wholly or in part for heating and ventilating 
flues. 

Tests of Concrete Fence Posts. — In the summer of 
1904 a number of reinforced concrete fence posts were 
made for experimental purposes, with a view to deter- 
mining their adaptability for general use. These posts 
were made both with and without reinforcement, and 
tested at the age of 90 days. The reinforcement, rang- 
ing from 0.27 per cent, to 1.13 per cent., consisted of 
four round steel rods, one in each corner of post about 
1 inch from surface, the posts having a uniform cross- 
section of 6 by 6 inches. The posts were molded in a 
horizontal position, as this was found by trial to be more 
satisfactory than molding them vertically. 



HOW TO USE THEM 371 

The concrete was mixed moderately soft, crushed stone 
between 1 inch and i/4 iiich and gravel under % inch 
being used as aggregate. River sand, fairly clean and 
sharp, was employed with Portland cement. The posts 
were tested as beams, supported at both ends and loaded 
at the centre, with spans varying from 4 feet to 5 feet 6 
inches. An attempt was made to prevent slipping by 
providing the reinforcing rods with collars and set 
screws at the ends, but in every case, with but two ex- 
ceptions, the rods slipped under a comparatively light 
load, thus showing the necessity for some form of me- 
chanical bond. As would be expected, those posts which 
were not reinforced possessed very little strength. 



w 



t-/^4- 



"ntf 



■ 4rO' 



Method of testing 
posts under static loads. 



A series of tests was made with sheet-iron reinforce- 
ment, in the form of round and square pipes, embedded 
in the posts, but these posts, though developing consid- 
erable strength, proved less economical than those rein- 
forced with plain rods, and at the same time were less 
simple in construction. The results of these tests, as re- 
corded in Table I., do not properly represent the strength 
of similar posts in which some form of mechanical bond 
is provided to develop the full strength of the reinforce- 
ment. 



372 



CEMENTS AND CONCRETES 



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HOW TO USE THEM 



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374 CEMENTS AND CONCRETES 

In order to obtain more data on the subject, this in- 
vestigation has been supplemented by a second series of 
tests, the results of which form the subject matter for 
the sections on concrete fence posts and are expressed 
numerically in Table II. 

In these tests it was decided to make the posts taper- 
ing in order to economize material and reduce their 
weight. For the concrete, Portland cement, river sand, 
and gravel were used in the proportion l-2%-5, meas- 
ured by volume, the gravel being screened below 1/2 inch. 
Sufficient water was used in mixing to produce a plastic 
mass, requiring only a moderate degree of tamping to 
bring water to the surface. The posts were molded and 
kept under wet burlap for four weeks, and tested at the 
end of sixty days. The reinforcing members were placed 
in the corners of the posts about 1 inch from the surface, 
being looped and bent, as indicated in Table II. These 
posts were not designed with a view to developing the 
ultimate compressive strength of the concrete, but where 
greater strength is necessary it may be obtained at small 
expense by increasing the percentage of reinforcement. 
It is important that fairly rich concrete should be used 
in all cases to enable the posts to stand exposure and to 
prevent chipping. 

All of these posts measured 6 by 6 inches at the 
bottom and 6 by 3 inches at the top, except Nos. 29, 
30, 31, 32, 33, and 34, which Avere 6 by 6 at the 
bottom and 3 by 3 at the top. It will be noticed that the 
saving in concrete introduced in the construction of these 
posts is accompanied by a marked decrease in strength 
as compared with the other posts similarly reinforced. 
It would also appear that the twisted wire has a slight 



HOW TO USE THEM 



375 



Table II. Showing the Strength of Reinforced 

Concrete Fence Posts. 



Drawn steel rods 
....do 



Kind of rein- 
forcement. 



do 

do 

do 

do 

do 

do 

do.> 

do 

do 

Twisted fence wire 
do 



....do 

....do 

....do 

....do 

....do 

....do 

....do 

....do 

Barbed wire 
....do 



do 

do 

do 

do 

do 

do 

do 

do 

do 

do 

Drawn steel rods 

do 

do 

Twisted fence wire 

do 



•»3 

a 

a 

o 
t-l 
o 

"S a 

03 0) 

a; »2 

U CO 

ei OS 
o 

X 

eS 



O 



0.08 
.08 
.08 
.08 
.08 
.08 
.19 
.19 
.19 
.19 
.19 
.06 
.06 
.06 
.06 
.06 
.06 
.13 
.13 
.13 
.13 
.06 
.06 
.06 
.06 
.06 
.06 
.06 
,06 
.13 
.13 
.13 
.13 
.08 
.19 
.19 
.06 

.06 



a 



o 



o 
ei 

o 
13 

03 

O 



800 

820 

640 

795 

940 

740 

1140 

1170 

1020 

760 

820 

825 

755 

800 

815 

770 

780 

1550 

1275 

1200 

1500 

980 

820 

590 

745 

590 

550 

560 

480 

680 

840 

1280 

800 





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03 


03 ss 


S 


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1120 


218 


1145 


224 


1080 


175 


1040 


217 


1170 


257 


1075 


202 


1280 


311 


1885 


319 


1950 


278 


1945 


207 


1925 


224 


935 


225 


905 


206 


940 


218 


935 


222 


980 


210 


975 


213 


1920 


423 


1670 


348 


1830 


328 


1955 


410 


980 


268 


820 


224 


740 


161 


745 


203 


590 


161 


640 


150 


635 


153 


530 


131 


1040 


186 


1010 


229 


1515 


349 


1375 


218 


3d by 


impact 



-M 
O 

o 

I 

a 
o 

-a 

03 

o 

I—* 

S' 

a 

•f-H 

a 



F-H \ 



u 
> 



306 
313 
295 
284 
319 
293 
349 
515 
532 
531 
526 
255 
247 
257 
255 
268 
266 
524 
456 
500 
534 
268 
224 
202 
203 
161 
175 
173 
145 
284 
276 
414 
375 



.do 
.do 
•do 

.do 



Form of reinforcement. 



c 



\- 



l 



»»■!■ ■■■■■l»l|l» 



376 



CEMENTS AND CONCRETES 



advantage over the barbed wire as a reinforcing material, 
particularly when two wires are used in each corner of 
the post. ~ 

As stated before, it is impracticable to make a rein- 
forced concrete fence post as strong as a wooden post of 
the same size, and this is more especially true if the post 






^ 




|]]3™uJ 




First method of testing posts, 
by impact. 

NO. 17. 



has to withstand the force of a sudden blow or impact. 
In order to study the behavior of these posts under im- 
pact, a number of them were braced, as illustrated in 
No. 17, and subjected to the blow of a 50-pound bag of 
gravel, suspended from above by a 9-foot rope. The 
first blow was delivered by deflecting the bag so as to 
give it a vertical drop of 1 foot, and for each successive 



HOW TO USE THEM 



377 



blow the drop was increased 1 foot. None of the posts 
showed any signs of failure under the first blow. Posts 
Nos. 14 and 20 cracked under the second blow, and failed 
under the third. Post No. 6 cracked under the second 
blow, which cracked open under the third blow, causing 
a momentary deflection of 5 inches. Posts Nos. 7 and 8 
each developed a crack under the second blow, but 
showed no further signs of weakness after the fifth blow. 



c- 






1 



Second method of testing 
posts by impact. 

NO. 18. 



other than a slight opening of the initial crack. In each 
case the only crack developed was at point A. Posts 6, 
7, and 8, which cracked but did not fail under the im- 
pact test, were further tested, as indicated in No. 18, by 
raising the small end and allowing them to drop from- 
successive heights at 1, 2^ 3 and 4 feet. Under this test 
a number of cracks developed, but in no case did the re- 
inforcement fail. 

Although it might appear from these results that posts 
as here described have hardly enough strength to recom- 
mend them for general use, it should be remembered that 
in many cases fence posts are not subjected to impact. 



378 



CEMENTS AND CONCRETES 



and it may prove more economical to replace from time 
to time those whicli fail in this way than to use wooden 
posts, which, being subject to decay, must all be replaced 
sooner or later. 




Diagram showing the effect of clay on cement mortars. 

NO. 19. 



Refempering. — Table III. illustrates the effect of re- 
tempering Portland cement mortar. The mortars used 
consisted of Portland cement and crushed quartzite be- 
tween 1 and 2 millimeters in size, mixed in different pro- 



HOW TO USE THEM 



379 



portions. In each case, after the initial or final set had 
taken place, sufficient water was added in retempering to 



TABLE III.— Effect of Ketempering on Cement Mortars. 





Tensile Strength, in Pounds Per 
Square Inch. 


Treatment of Mortar. 


Neat 

Cement. 

a 


IPart 

Cement, 

IPart 

Sand.ft 


IPart 
Cement, 
2 Parts 
Sand, c 


IPart 
Cement, 

3 Parts 
Sand, d 


Mortar made up into briquettes . 
immediately after mixing 


651 
650 
673 
634 
679 


624 
701 
624 
581 
610 


527 
493 
529 
480 
492 


417 
385 
421 
403 
409 


Average 


657 


628 


504 


407 


Mortar allowed to take initial 
set, then broken up and made 
into briquettes 


671 
593 
644 
633 
724 


692 
670 
654 
676 
700 


589 
554 
559 
534 
532 


326 
349 
330 
358 
267 


Average 


653 


678 


554 


326 


Mortar allowed to take final 
set, then broken up and - 
made into briquettes 


455 
522 
525 
558 
642 


527 
569 

587 
566 
568 


492 
491 
497 
486 
531 


364 
380 
361 
315 
345 


Average 


540 


563 


499 


353 



a Initial set, 1 hour 42 minutes; final set, 7 hours 15 minutes. 
b Initial set, 1 hour 30 minutes- final set, 7 hours 15 minutes, 
c Initial set, 2 hours; final set, 7 hours. 
d Initial set, 2 hours 20 minutes; final set, 7 hours. 



restore normal consistency. The briquettes were tested 
at the age of four months. 



380 CEMENTS AND CONCRETES 

Some Practical Notes. — Spencer B. Newbury, who is 
an authority on the subject, says ''that the making of 
good cement concrete is a comparatively simple matter, 
and yet, like most simple operations in engineering, there 
is a right way and a wrong way of doing it. Probably 
nine-tenths of the concrete work done falls far short of 
the strength it might develop, owing to the incorrect pro- 
portions, use of too much water, and imperfect mixing. 
All authorities are agreed upon the importance of thor- 
ough mixing and the use of the minimum quantity of 
water in all classes of concrete work. The matter of cor- 
rect proportions of cement, sand, broken stones, etc., is 
one which requires some thought and calculation, and by 
proportioning these ingredients correctly an immense 
saving in cost and increase in strength can easily be se- 
cured. 

The chief object in compounding concrete is to pro- 
duce a compact mass, as free as possible from pores or 
open spaces ; in short, to imitate solid rock as closely as 
possible. Cement is the "essence of rock" in portable 
form, and by its judicious use granular or fragmentary 
materials may be bound together into solid blocks of any 
desired size and shape, which in strength and wearing 
qualities are at least equal to the best stone that comes 
from the quarries. Cement is, however, very costly in 
comparison with the other ingredients of concrete, and 
must not be used wastefully. A little cement, judi- 
ciously used, is better than a large quantity thrown in 
recklessly, as a little study of the principles involved 
will plainly show. 

To produce a compact mass from fragmentary ma- 
terials, the voids must be filled. Imagine a box holding 1 
cubic foot. If this were filled with spheres of uniform 



HOW TO USE THEM 381 

size, the voids or open spaces would be one-third the total 
volume, or 33 1-3 per cent., with spheres of various sizes, 
as, for example, from large marble down to fine shot, the 
voids would be much less, and it would theoretically be 
possible, by the use of spheres of graded sizes, from the 
largest down to dust of infinite fineness, to fill the box 
completely, so that there would be no voids whatever. In 
practice it is well known that the use of materials of 
varying fineness gives the best concrete, since the voids 
are much less than in materials composed of pieces of 
uniform size. Hence the common practice of making 
concrete with cement, sand and broken stone, instead of- 
with cement and sand, or cement and stone only. The 
sand fills the voids, and if the proportions are correct, a 
practically solid mass results. As an example of this, 
the writer found the briquettes of cement with three 
parts of sand and four parts gravel showed higher ten- 
sile strength at 28 days than those made with three parts 
sand only. 

The following table gives the relative weights of a 
given volume of different materials, and also the per- 
centage of voids, as determined by the writer. The ma- 
terials were shaken down in a liter measure by giving 
one hundred taps on the table, and weighed. In the case 
of the broken stone a larger measure was used. The 
voids were calculated from the specific gravity. 

Comparison of the three different grades of Sandusky 
Bay sand shows how greatly the percentage of voids 
varies with the proportion of fine and coarse grains pres- 
ent. The first is the natural sand, not screened, as 
pumped up by the sand sucker from the bottom of the 
bay, and contains a large amount of fine gravel. The 
second is the same, passed through a 20-mesh screen to 



382 



CEMENTS AND CONCRETES 



remove the coarse particles. It will be seen that this 
operation increases the proportion of voids from 32 to 
38 per cent. The third is the same sand passing a 20- 
mesh and retained on a 30-mesh screen, thus brought to 
the fineness of the "standard sand" used in cement test- 
ing. This shows 40.7 per cent, of voids, owing to the uni- 
form size of the grains. The same relation is seen in the 



WEIGHT OF UNIT MEASURE AND PERCENTAGE OF VOIDS IN 

VARIOUS MATERIALS. 



Portland cement 

Louisville cement 

Sandusky Bay sand, not screened 

Sandusky Bay sand, through 20-mesh 

screen 

Sandusky Bay sand, 20-30 mesh (standard 

sand) 

Gravel, /i to % inch 

Gravel, /i to yV inch 

Marblehead broken stone (chiefly about 

egg size) 



Weight 
of 1 Liter. 



1720 g 

i780g 

1630 g 

1570 g 
1510 g 
1680 g 

1380 g 



Per Cent 

of 

Voids. 



32.3 

38.5 

40.7 
42.4 
35.9 

47.0 



two grades of gravel given in the table, that containing 
finer grains showing much the lower percentage of voids. 
These figures illustrate the imprudence of screening 
any of the materials used in making concrete. The pres- 
ence of clay in sand is, however, objectionable, not be- 
cause of its fine state of subdivision, but because the 
clay coats the sand particles and prevents the adhesion 
of the cement. Such sand might be improved by wash- 
ing, but probably not by screening. It has been found 



HOW TO USE THEM 383 

tliat cement which has been ground to dust with an equal 
amount of sand goes much further when used for con- 
crete than the same quantity of cement when used in 
the ordinary way. This is doubtless owing to the fact 
that the sand dust aids in filling the voids. It is also 
well known that slaked lime, when added to cement mor- 
tar, greatly increases the strength of mixtures poor in 
cement. 

From the figures given in the above table the compo- 
sition of a theoretically perfect concrete may readily be 
calculated. The existence of voids in the cement may be 
disregarded, since in the process of hardening the cement 
sends out crystals in all directions, completely encrusting 
the sand particles and practically filling all the voids 
which the cement itself contains. Examination of a 
well-hardened briquette of cement with 3 parts sand, 
after breaking, with the aid of a lens, will show this 
clearly 

Suppose, for example, we wish to make the best pos- 
sible concrete from Portland cement with the sand and 
gravel given in the above table. We should, of course, 
choose the unscreened sand and gravel as containing 
the least proportion of voids. One hundred measures of 
gravel would require 35.9 measures of sand. As the 
sand contains 32.3 per cent, of voids, we require 32.3 
per cent, of 35.9, or 11.6 measures of cement. The pro- 
portions would, therefore, be : Cement, 11 ; sand, 3, and 
gravel, 9. It is customary, however, to increase the pro- 
portion of mortar (cement and sand) by about 15 or 20 
per cent., in order that the coarser materials may be 
completely coated with the finer mixture. Making this 
addition, we find the concrete proportions to be : Cement, 
1 ; sand, 2.8 ; gravel, 7. Allowance must also be made in 



384 CEMENTS AND CONCRETES 

practice for imperfect mixing, since the materials can 
never be distributed in a perfectly uniform manner. 
Practically, with these materials, a concrete of cement 
1, sand 2%, and gravel 6, would probably give the best 
result, and little or no improvement would result from 
increasing the proportion of cement. 

A similar calculation shows that the correct propor- 
tions for a concrete made of the sand and broken stone 
given in the table would be 1 to 3 to 6%. Increasing 
the amount of cement and sand by 20 per cent., we have 
1 to 3 to 5V9. Probablv 1 to 2y-> to 5 would be found to 
give the best results in practice. The determination of 
the voids in the sand, gravel and broken stone used is 
of the greatest value in adjusting the proportions of 
concrete. 

The simplest method of determining this in the case of 
gravel and broken stone is to have a metal box made of 
1 cubic foot capacity; this is filled with the materia,l to 
be tested, well shaken down and struck off level. Thb 
box and contents are then weighed. Water is now 
I)Oiured in until it rises even with the surface, and the 
total weight again taken. The difference in the weights 
is tlie weight of the water filling the voids of the ma- 
terial. Now 1 cubic foot of water weighs 64 4-10 lbs., 
and from the weight of the water found the percentage 
of voids can be simply calculated. For example, in one 
experiment the box and broken stone weighed 88 lbs. 
After filling the spaces in the stone with water the 
weight was llYi/s lbs., a difference of 291/2 lbs. The 
percentage of voids is, therefore, 29^x100 divided by 
62.4 equals 47 per cent. 

In the case of sand this method will not answer, as it 
is difficult to completely fill the voids of the sand by 



HOW TO USE THEM 385 

adding the water. The voids can, however, be readily 
calculated from the weight of a cubic foot and the spe- 
cific gravity. The specific gravity of quartz sand is 
about 2.65. A cubic foot of sand, free from voids, would 
therefore weigh 2.65x62.4 equaling 165.4 lbs. The 
weight of a cubic foot of sand, well shaken down, was, 
however, found to be only 112 lbs,, a difference of 53.4 
lbs. The proportion of voids was, therefore, 53.4x100 
divided by 165.4 equals 32.3 per cent. The percentage 
in voids in clean natural sand does not vary greatly, and 
may be taken as 33 to 35 per cent, for coarse and 35 to 
38 per cent, for fine sand. 

We have already seen that with the materials above 
described, concrete composed of 

Cement 1, sand 2%, gravel 6, or 

Cement 1, sand 2%, broken stone 5 
by measure, will be practically compact and non-porous, 
and that there is no object in increasing the proportion of 
cement. Such concrete, if made from Portland cement, 
will, however, be rather expensive, requiring about one 
barrel of cement (equals 3% cubic feet) for every, cubic 
yard. This is unnecessarily good for ordinary work, and 
will only be required for foundations of engines and 
other heavy machinery, in which the best possible result 
must be secured regardless of cost. In cheaper concretes 
the relative proportions of sand and broken stone should 
be the same, as determined by the voids in the coarser 
materials, while the proportion of cement may be varied 
according to the required conditions of quality and cost. 
Mo^t excellent concrete may be made by using: 

Portland cement 1, sand 7, stone or gravel 14, 

Here are specimens of these two concretes, taken from 
trial blocks laid Oct. 1, 1894, to determine the best pro- 



386 



CEMENTS AND CONCRETES 



portion for the foundation of brick pavement. The 
richer of the two, 1-5-10, is certainly good enough for 
any purpose, even for engine foundations. A cubic yard 
of such concrete requires about % barrel of cement ; the 
total cost of the cement^ sand and stone is about two 
dollars per cubic yard. This is no more expensive than 
concrete made from Louisville cement with 2 of sand 
and 4 of broken stone, and is immensely superior to the 
latter in strength. 

The following table shoAVS the results obtained in 
Germany by R. Dykerhoff in determining the crushing 
strength of various concretes. The blocks used were 2% 
inches square, and were tested after one day in air and 
27 days in water. 



Proportions by Measure. 


strength under Compression. 


Portland 
Cement. 


Sand. 


Gravel. 


Pounds per Square Inch. 




2 

2 
2 

3 
3 
3 

4 
4 
4 


• • 

3 
5 
5 

• • 

5 

m» 

5 

8X 


2125 
2747 
2387 
978 
1383 
1632 
1515 
1053 
1273 
1204 



These figures prove the statement already made, that 
mixtures of cement and sand are strengthened, rather 
than weakened, by the addition of a suitable quantity 
of gravel. It will be noticed that the mixture — cement 1, 



HOW TO USE THEM ' 387 

sand 2, gravel 5 — is actually stronger than cement 1, 
sand 2, without gravel. The same is shown in the mix- 
tures 1 to 3 and 1 to 4. 

In estimating the amount of material required to pro- 
duce a given volume of concrete, it may be stated that 
when very strongly rammed into place the volume of 
concrete obtained from correct proportions of the ma- 
terials will be about 10 per cent, more the volume 1 cubic 
foot cement, 2% cubic feet sand, and 5 cubic feet stone, 
and will therefore yield about 51^ cubic feet concrete. 

Another Concrete Stairway and Steps. — A good stair- 
case is one of the essential features in a building. The 
safety and convenience of persons using a staircase are 
not only affected by the due proportions and arrange- 
ments of the steps, but by the strength and fire-resisting 
properties of the materials employed, and the manner of 
construction. The wells are in many cases too small, 
out of proportion to the structure, which necessitates 
dangerous winders, tiring high risers, narrow treads, or 
insufficient headway. Some architects when designing a 
staircase pay little attention to the practicability of con- 
struction. What may seem easy in theory or on paper 
is often found impracticable or unnecessarily difficult 
when reduced to actual practice. The errors of omission 
and commission are left for the workmen to contend 
with and overcome as best they may at the employer's 
expense. Happily such cases are few, the majority of 
architects supplying figured drawings, which are not 
only a help and guide to the workrnen, but also ensure 
a practical staircase in due proportion and without un- 
necessary expense. Staircases should be spacious, light, 
and easy of ascent. It is generally admitted that a 12 
inch tread and a 6 inch rise is the most convenient, and 



388 CE3IEXTS AND CONCRETES 

that uo trtacl slioiild be less than S inches or more than 
16 inches, and no rise less than -i^o inches and more than 
7 inches. Accordina- to Blondel. the rise should be re- 
duced 14 iiich for every inch added to the tread, or the 
tread reduced bv 1 inch to ever\^ M> inch added to the 
riser, taking a 12 inch tread and a 6 inch rise as the 
standard. Treads mav be increased bv means of a nos- 
ing. which nsnally projects from 1 inch to l^o inches. 
Nosing not only gives more available space for the tread, 
but also affords some advantage to persons going down 
stairs, as the heel cannot strike against the rising. In 
setting out a flight of stairs, the tread of the steps are 
measured from riser to riser, ^here practicable, the 
number of steps from landing to landing should be odd. 
because when a person begins to ascend with the right 
foot first (as most people do) he should end with the 
same foot. Rectangular steps are called fliers. Wind- 
ers, being narrowed at one end. are always more in- 
convenient and dangerous than straight steps, and 
should not be used for public buildings or other places 
where there is a crowded traffic. TTinders are also 
more expensive to construct. They are, however, un- 
avoidable in circular staircases, also in some instances 
in angles, where a quarter or half space landing would 
not give the desired rise. AVinders should be so made 
that the tread 6 inches from the end of the narrow 
point should be wide enough to step upon without dan- 
ger of slipping. No stairs should be less than three 
feet from the wall to the hand-rail. A width of 3 feet 
6 inches will allov^ tAvo persons to walk arm in arm up or 
down stairs. A width of 4 feet 6 inches is generally used; 
this gives plenty of space for two persons to pass each 
other. No hard and fast rules can be laid down for the 



HOW TO USE THEM 389 

size of* treads and risers, as they are regulated more 
or less by the size of the well and the height from floor 
to floor. Too few steps in a flight are as bad as too 
many. There should not be less than three. Long 
straight flights of steps are tiring and dangerous. The 
straight line of length should be broken by landings, 
so that there may not be more than eleven continuous 
steps. Landings give ease in ascending and safety 
when descending. No landing should be less in length 
than the width of the staircase. The staircases in the 
pre-Elizabethan style were usually plain, dark and in 
long narrow flights; but with the Elizabethan archi- 
tecture came in a more commodious, light and decora- 
tive style. Wood stairs are often enriched with plaster 
work, the soffits being panelled with plaster, and the 
strings adorned with composition or plaster enrich- 
ments. >Stone stairs are also frequently enriched with 
plaster mouldings in the angles of the soffits and walls. 
External steps and landings are usually made with a 
fall of ^^ inch to the foot to allow rain to fall off. 

Cast Concrete Stairs. — Concrete is now fast super- 
seding stone, wood and iron for staircase construction, 
where strength, durability and economy and fire-resist- 
ing properties are required. Cast concrete stairs were 
first introduced nearly sixty years ago. The stairs 
Avere cast in single steps, or in treads or risers, and 
fixed in the same way as natural stone. Square and 
spandrel steps, risers and treads are cast in wood 
moulds ; circular steps and curtails in plaster moulds. 
Spandrel steps should have the wall or "tail" end 
formed square, and about 4% inches deep, to give a 
better bed and bond in the wall. A good mixture is 3 
parts of granite or slag chippings and 1 of Portland 



390 CEMENTS AND CONCRETES 

cement, ganged stiff, and well rammed into the moulds. 
When set they are removed from the moulds, air dried, 
and placed in water or a silicate bath, and treaded in 
a similar way to that described for slabs. For long 
steps pieces of T iron, or iron pipes, are sometimes in- 
serted in the centre of the concrete while being cast. 
The iron is not actually required to strengthen con- 
crete properly made, but is used to give a temporary 
strength to the cast while it is green, so as to allow 
more freedom and security in handling the cast when 
it is being taken from the mould and moved about till 
permanently fixed. Landings are cast in a similar way, 
but unless very small, they are best done in situ. I 
have made landings up to 40 feet superficial, but owing 
to the cost of transit, hoisting and fixing they were 
not profitable. 

Tests of Steps. — The following examples show the 
strength of concrete steps : In Germany, when con- 
structing a concrete stair, with square- steps 3 feet 4 
inches long, and 6-inch tread, and Gi/o-inch rise, and 
one end set 8 inches into the walls, four steps were sub- 
mitted for trial, and 5,940 lbs. weight of iron were 
gradually piled on them. The steps showed no signs 
of fracture, but no more Aveight could be put on be- 
cause the masonry began to yield. The load was left 
on three days, and the steps remained unaffected. Al- 
though numerous tests have been made of concrete 
floors and blocks, few have been made for concrete 
steps. The following may be given as a reliable one: 
The steps were about 6 feet long, 11-inch tread and 
6-inch rise. Every step was tested in the presence of 
the foreman concreter and author. The steps were 
supported at both ends, and weighed with a distribu- 



HOW TO USE THEM 391 

tive load. The majority, which were matured by age, 
passed the specification standard. 

Concrete Stairs Formed ''in Situ.'^ — Concrete stairs 
are an outcome of stairs built with cast concrete steps. 
Stairs formed in situ were introduced in 1867. The 
idea was suggested by the use of reverse moulds for 
fibrous plaster work, and in the formation of concrete 
dormer windows made in situ on some mansions. The 
step landings and the wall bond, being a monolith 
structure, were to a certain degree self-supporting. 
They tend to strengthen instead of to weaken the 
walls. Architects generally supply drawings of the 
intended staircase, but as there is often a differ- 
ence in the size of the details of the actual work and 
the drawings^ it is necessary that the workman should 
have a practical knowledge of setting out the "height" 
and "go" for the pitch board, to suit the landings and 
the well of the staircase, and ensure the necessary head- 
room. 

Setting Out Stairs. — A correct method of setting out 
the framing for concrete stairs is of primary import- 
ance. The height of a stair is the length of a per- 
pendicular line drawn from the upper of a floor to 
that of the one immediate^ above it. The "go" is 
the length of a horizontal line drawn along the centre 
line of the flight of steps or stair space. The exact 
height and widths should be taken on a rod, which 
should afterwards be used for setting out the work. 
Never work without this rod, as it is quicker and more 
accurate than measuring with a 2-foot rule. There are 
various ways of getting the dimensions of treads and 
rises. The following is a simple one and answers for most 
purposes. The height and go are taken and suitably 



392 CEMENTS AND CONCRETES 

• 

divided. For example, if the height from floor line tc» 
floor line is 9 feet 3 inches, and it is proposed to 
make each rise 6 inches high, reduce the weight to 
inches, which would be 111 ; divide by the proposed 
height of each step — 6 inches — the quotient will be 18, 
giving the same quotient 6 and 3-18. If there are 
intermediate landings, or half spaces, their dimensions 
must be allowed for. The size of the tread is obtained 
by dividing the '^go" by the number of steps. The 
quotient will be the width of the tread. Great care 
should be taken in setting out the rods and pitch 
boards. It is better to measure thrice than to cut twice. 
When the string line is marked on the wall, a chase 
about 4% inches deep is cut into the wall. It is not 
necessary to cut the chase straight at the soffit line, as 
it is apt to cut into a half,, or rather a whole brick, 
and leave the ends loose. The irregular line of chase 
below the soffit line can be made solid during the pro- 
cess of filling in the steps. The chase should be cut 
as the work proceeds. Not more than one flight at a 
time should be cut, to avoid weakening the wall. In 
some instances a brick course in sand is left by the 
bricklayers. The bricks are then taken out as the 
work proceeds. 

Nosings and Risers. — ^Nosing mouldings should be 
strong and bold. A simple but well-defined moulding 
not only gives greater strength, but is more in keep- 
ing with its purpose than one with numerous or small 
members. Nosing and riser moulds are best formed 
in two parts, the nosing moulds being one part and the 
riser board the other. To cut them out of the solid 
would not only be expensive, but also cumbrous to fix. 
They can be run at most saw and moulding mills. 



HOW TO USE THEM 



393 



Tliev should be nin in lengths and then cut and mitred 
on the job. Hlustration No. 20 shows various forms 
of nosing". Fig. 1 is a simple nosing for common work. 
Fig. 2 may be used for school stairs, etc. Figs. 3 and 
4 are well adapted for a good class of work. It will be 
seen that the lower edges of the' riser boards are 
splayed. This is to admit the shoe of the running 
mould; also a trowel to work close up to face of the 



Fig. I. Fig. 2. Fig. 3. Fig. 4* 
1^ 






X 



S'ections "of Nosing 
IVlouLDS WITH "Riser Boards. 

NO. 20. 



concrete riser when running and trowelling off the 
treads. The dotted lines indicate the line of tread. 
Nosing moulds are cut in the centre of the section, and 
afterwards the two parts are held in position with 
screws while the steps are being filled in. This allows 
the upper part to be unscrewed and taken off when the 
stuff is nearly set, thus allowing more freedom to 
trowel the surface of the tread; also to make a better 
joint while the stuff is green, and at the part that is 
cast and the part to be trowelled. The joint in the 
nosing mould leaves a thin seam which is easily cleaned 
off, w^hereas the joint of the tread and nosing is not 
only seen more, but is also more difficult to make good. 



394 



CEMENTS AND CONCRETES 



Illustration No. 21 shows the mould and joint and 
screws for fixing same. 

Framing Staircases. — The wood framing for con- 
crete stairs differs from and is partly the reverse to 
that used for wood stairs. The nosings are formed the 
reverse of the moulding, and the whole framing is so 
constructed that it forms a mould to cast all the steps 
and landings, from floor, in monolithic form, or one 
piece. When the positions of half spaces or other 




Jointed Nosincj Mould 

WISTH 'KiSER BOAKEE. 
NO. 21. 

landings are set out on the walls, strong planks are 
fixed on edges so as to give fixing joints for the car- 
riage and outer strings. The strings are then fixed 
to act as guides for fixing the centring, risers and nos- 
ing moulds. Where practicable, the outer string should 
be so arranged in the fixing that it can be taken off 
after the concrete is firm without disturbing the cen- 
tring. This allows the returned ends of the steps to 
be cleared off while the work is green. The carriage 
boards are fixed from landing to landing. Illustra- 
tion No. 22 shows the forms and positions of the vari- 



HOW TO USE THEM 



395 




S3 



Q 
y 



d 

w 

H 
W 

S (M 

o 

o 

fa 

o 






396 CEMENTS AND CONCRETES 

ous parts, with their names. Bullnoses or curtails and 
circular parts of nosings are formed in plaster moulds, 
which are run with several reverse running moulds. 

Staircases between walls are more simple than open 
staircases; therefore they are more eas}^ to frame up. 
The string boards are cut to the reverse of that used 
for wood stairs. A string is cut for each wall. The 
riser boards are then fixed to the wall strings. The 
centring for the soffits is fixed independently^ the 
boards being laid on fillets which are nailed on each 
wall. For short flights of steps or common stairs, such 
as for cellars, etc., string boards may be dispensed with. 
The positions and sizes of the risers, treads, soffits and 
landings are first set out and marked on the walls. 
Riser fillets are then nailed on the walls, taking care 
to keep each fillet in a line with the riser mark, and 
to allow for the thickness of the riser boards which 
are subsequently nailed on the inner sides of the fillets. 
Riser boards for winders are generally hung on long 
fillets and then nailed on the walls. Long fillets ex- 
tending upwards enable the work to be easier and more 
strongly fixed, as they cover more brick joints than if 
cut to the exact height of the riser. 

Cent ting for Landings and Soffits. — Centring for 
landings and the soffits of st-airs should be made strong 
and true. The timber should be well seasoned, to pre- 
vent warping or shrinkage. The outer angles of land- 
ings should be supported by strong wood props, not 
only to carr}^ another prop for the landing above. All 
centrings should be made perfectly rigid, to stand the 
weight of the concrete and the ramming. Great care 
should be taken that the timber framing is securely 
supported, as any deflection will not only throw the 



HOW TO USE THEM 397 

work out of level, but will also tend to crack tlie con- 
crete. The principal props should be cut about % 
inch shorter than the exact height. They are placed 
on a solid bed, the %-inch space at top being made 
up with two wedges, the thin ends being inserted in 
opposite directions and gently driven home from each 
side until the exact height is obtained. If it is dif- 
ficult to get the top of the prop, the wedges can be 
inserted at the bottom. The use of the wedges will 
be seen when the centring is struck. If there are 
winders in the stairs, the centring for the soffit will be 
more or less circle on circle. This form of centring 
is done by lathing, with 1-inch boards, cut to a taper, 
the surface being made fair with a gauged lime and 
hair. Rough 1%-inch boards are used for the centring. 
This should be close-jointed. Open joints or sappy 
timber act as a sieve, and allow liquid cement to drip 
through^ thus robbing the concrete of its strength. 

Waterproof CentringM — The following is a method 
that has been used with marked success for the sof- 
fits of stairs, landings and the ceilings of floors. The 
initial cost of preparing is small, and is repaid with 
interest by the decreased cost of setting and the in- 
creased strength and solidity. For ordinary work, 
such as warehouses, etc., it is very suitable, as a fin- 
ished surface is formed, and no setting required. It 
seems strange that, when casting concrete work out of 
a wood or a plaster mould, the mould is seasoned, and 
every precaution taken, not only to stop suction, but 
also to prevent the escape of liquid cement; but when 
casting a large surface in situ (where every precau- 
tion should be taken to obtain the maximum of 
strength), any kind of centring (which is a mould) 



398 CEMENTS AND CONCRETES 

is thought good enough, if only sufficiently strong to 
carry the concrete till set. I am aware that many 
workers in concrete think that an open or porous 
centring is a benefit instead of a defect, simply be- 
cause it affords an escape for excess of water. But 
why have excess of water at all? There is no gain 
in time or strength, but a direct loss in both points. 
The excess water descends through the concrete by 
force of direct gravitation, and always carries a cer- 
tain amount of liquid cement with it to the centring, 
leaving the aggregate more or less bare, and the body 
of the concrete weak. A part of the liquid cement 
also oozes through the joints and crevices, which leaves 
the skin of the concrete bare and broken. There is 
no reason or excuse for excess Avater, and it is simply 
the result of ignorant or careless gauging, which is not 
only a waste of time, water and cement, but a loss in 
the ultimate strength, and the cause of cracks. Porous 
centring is also a dirty process. The overhead drip, 
drip, is neither good for the workmen nor the material 
underneath. 

The process of forming the rough centring boards 
watertight is simple and expeditious, being done by 
laying the rough board surface with a thin coat of 
gauged plaster ; and when the centring has been struck 
the plaster will come with the boards, leaving the con- 
crete Avith a fair face. The ramming forces a certain 
amount of water to the loAver surface or centring, and 
this is so close and fine that it takes an exact impress 
of it; consequently the truer and smoother the centring 
the truer and smoother the concrete surface. The film 
of water indurates the skin of the concrete and prevents 
surface or water cracks. It will be noticed when filling 



HOW TO USE THEM 399 

in dry or porous plaster moulds that the concrete cast 
produced has a surface either friable when newly cast, 
or when dry the surface is full of small water lines, 
like a map, or a broken spider's web. This is owing 
to the suction caused by the porous nature of the mould 
and the water escaping through the weak or open parts 
leaving corresponding lines on the concrete surface. 
These defects are obviated by using waterproof cen- 
tring. 

Where fineness of finish is not required, such as ware- 
house floors^ the surface can be made, sufficiently fair 
and smooth when filling in the concrete without sub- 
sequent setting. The plaster is laid on the centring, 
and made fair and smooth, and then the surface is 
saturated with water to correct the suction; or the 
surface, if dry, may be brushed over with a thin soap 
solution to prevent adhesion. On this surface a coat 
of neat cement about Ys inch is laid, and on this the 
concrete is placed. The two unite in one body, and 
when set, and the centring struck, the plaster sheet 
comes with the boards, leaving a smooth surface. This 
surface can be made in color by lime washing, which 
will also give more light, or a finished white surface 
can be obtained by substituting parian or other white 
cement for the neat Portland cement. The concrete 
must not be laid until the white cement is firm, not set, 
otherwise the concrete will force its way in thin or 
soft parts and disfigure the surface. I have success- 
fully used this method for obtaining a finished sur- 
face when encasing iron girders with concrete for fire- 
proof purposes. 

Staircase Materials. — With regard to the materials 
for a concrete staircase, no one who intends to con- 



400 CEMENTS AND CONCRETES 

struct them substantially, fireproof and economically, 
can afford to use common substances, when by judi- 
cious selection and for a trifling additional first cost a 
combination of materials can be obtained, which, if 
not (strictly speaking) fireproof, is at least the most 
incombustible constructive compound known. This is 
a quality of the most vital importance in modern house 
construction. Portland cement and slag cement are 
the best known matrices. The finer Portland cement 
is ground, the greater its heat-resisting powers. Slag 
cement is lighter than Portland cement, aijd its fire- 
resisting properties exceed those of both gypsum and 
Portland cement. But as its manufacture is as yet 
somcAvhat limited, and its strength not uniform, ex- 
ceptional care must be exercised in testing its general 
qualities before using it for staircases. Broken slag, 
firebricks, clinkers and pottery ware are the best ag- 
gregates, being practically fireproof. All should be 
clean, and in various graduating sizes, from that of a 
pin's head to that of a walnut, for roughing out with. 
The topping should be the same as that described for 
Eureka paving. 

Filling in Stairs. — Before gauging the materials, 
sweep out all dust in the interior of the framing and 
the wall chase and then wet the latter, and oil the 
woodwork. If the wood of the nosing moulds and 
risers is sappy or open grained, the long lengths, be- 
fore being cut and fixed, should be made smooth and 
indurated by coating with a solution of hot paraffin 
wax. The smoother and less absorbent the surface of 
the wood, the more readily and cleaner will the mould 
leave the cast work. Paraffin also renders the wood 
damp-proof, thus preventing swelling or warping. For 



HOW TO USE THEM 401 

ordinary purposes one or two coats of paraffin oil will 
be found sufficient. This should be done two or three 
hours before the steps are filled in^ so as to allow the 
oil to partly dry in and stop the pores of the wood. 
If the wood absorbs all the oil, and has a dry sur- 
face, brush the surface again with paraffin, using a 
semi-dry brush. This should be done as the work pro- 
ceeds. If the surface is over wet, the oil mixes with 
the cement, thus causing a more or less rough sur- 
face. Soap solution may be safely used for rough 
concrete, or where a rough surface is left to be sub- 
sequently set. In the latter case the surface must be 
well wetted with water and scrubbed before the final 
coat is applied. Soap solution may also be used for 
rough framing, such as soffit boards, but soap should 
not be used for fine concrete or a finished surface, 
as it leaves a film of grease which has a tendency to 
prevent the cement adhering when clearing up or mak- 
ing good the finished surface. As the work of filling 
proceeds, the surface should be brushed over with a 
slip, that is, neat cement, to fill up all angles, and 
obtain a surface free from "bulbs" and ragged ar- 
rises. 

The coarse concrete for roughing out the stairs is 
composed of 1 part of Portland cement and 3 parts of 
coarse fireproof aggregate. These materials must be 
gauged stiff and laid in small portions of about a pail- 
ful at a time, taking care to thoroughly consolidate 
by ramming and beating with a wooden mallet, using 
a wooden punner or punch to get into the angles and 
deep parts. When the first layer, which may be about 
3 inches thick, is rammed, another layer is deposited 
and rammed, and so on until the rough stuff is within 



402 CEMENTS AND CONXRETES 

% inch of the line of tread. It must not be omitted to 
brush the strings, treads and nosing moulds with slip 
as the work proceeds. This is most effectually done 
bv the aid of a tool-brush. Care must be exercised 
when ramming stairs with mallets or punches that the 
mallet or other implement used is not too large or too 
heavv. for it would most likelv cause the framino- to 
bulge out. and the form of the work would be irre- 
trievably spoilt. During the operation of ramming 
some of the water and a part of the constituent of the 
cement is forced upwards, and leaves a thin, smooth, 
clayey film on the surface. Avhich prevents the adhesion 
of the next layer. For this reason the successive lay- 
ers should be deposited before the previous one is set, 
and the topping should be laid while the coarse con- 
crete is vet green. Too much stress cannot be laid upon 
the importance of topping the rough coat while it is 
green. This is one of the secrets of success of solid 
and strong work, so no more rough stuff should be laid 
than can be topped before the rough is set. 

The fine stuff for the topping is the same as for 
Eureka paving, viz., 1 part of cement to 2 parts of fine 
aggregate, gauged firm and plastic. The tread is made 
level and fair by means of a running mould so formed 
that it bears on the nosing moulds above and below the 
tread. The mould has a metal plate or '"shoe" fixed 
so as to run and form the tread. The shoe projects 
so that it will work under the riser board close up to 
the concrete riser. Illustration Xo. 23 shows a sec- 
tion of steps with the mould in position ; also a sec- 
tion of the nosing mould and soffit boards and car- 
riage. The end of the slipper next to the wall is cut 
short to allow the mould to run close up to the wall. A 



HOW TO USE THEM 



403 



section of a T iron is shown as sometimes used as an in- 
ternal support. Iron is used for long steps, or where 
stairs are intended for heavy traffic. Iron helps to sup- 




— Sections of Framing of Soffit of Stair, Riser 
And Noser Mould, with Concrete and Tread Run- 
ring Mould in Position. 

NO. 28. 



port the concrete until set; it is placed in alternate 
steps, or in every third or fourth step, according to the 
length of step. Ordinary sized steps require no iron, 



404 CEMENTS AND CONCRETES 

unless as a support for the concrete while green, and 
during the process of making. 

Finishing Stairs. — When the treads are firm after 
being run, the upper part of the nosing moulds are 
removed, the surface and joists trowelled off. The ad- 
vantages of having the nosing mould in two parts will 
thus be seen, as it allows the joint at this most notice- 
able part to be neatly cleaned off while the work is 
green. The lower part of the mould will support the 
concrete nosing during the finishing of the tread and 
until the concrete is set. If the work is done with a 
nosing mould in one piece, which necessitates its being 
left on until the concrete is set, the joint has then to be 
filed down and stopped, and however well done, has a 
patchy appearance. When the treads are finished, and 
the work set, but not dry, the riser and string boards 
are taken off, the joints made good, and the returned 
end of the steps cleaned off. If the stuff has been 
properly gauged and rammed, there should be little 
or no making good required, but it is important that 
if necessary it should be done while the work is green. 
A thin laver of neat cement will not adhere on a dense 
and dry body of concrete. The only way to obtain 
perfect cohesion is to cut the damaged surface out to 
a depth of not less than % inch, then thoroughly wet 
it, brush the surface with liquid cement, and fill it in 
with gauged cement. No traffic should be allowed on 
the treads during the process of setting and harden- 
ing. The work is further protected and hardened by 
covering with sacks kept wet for several days by fre- 
quent watering. Where there are several flights of 
stairs to construct, there should not be less than three 
sets of strings and riser boards, which will enable the 



HOW TO USE THEM. 405 

carpenter to fix one set while the plasterers are filling 
in and cleaning off the others. 

Non-Slippery Steps. — Incessant traffic tends to make 
the treads of steps more or less slippery. In order to 
obviate this, the surface is indented with a concrete 
roller, similar to that used for some kinds of paving. 
Another way is to form three or four V-shaped grooves 
from 1 inch to 2 inches apart on the treads while the 
concrete is moist. Another way is to insert leaden 
cubes about 1 inch square from 2 to 3 inches apart 
in the surface of the treads. Well-seasoned, hard 
wooden blocks, about the same size as the lead and 
fixed in a similar way, keeping the end grain vertical, 
are also used for this purpose. India rubber and cork 
cubes may also be used. 

Striking Centrings. — This should not be attempted 
until all the other work, with the exception of finishing 
the soffits, is done. It will be understood that the 
framing can be arranged so that the string and riser 
boards can be taken off without disturbing the soffit 
centring, which is kept up as long as possible. The 
time for striking centring greatly depends upon the 
class of cement used, the manner of gauging and lay- 
ing the concrete, and the temperature ; but generally 
speaking, centring should not be struck for at least 
ten days. A stair between the walls can be struck 
much sooner than one having only one bearing by which 
its own weight is carried. I have seen a stair, with 
steps projecting 3 feet 6 inches from the wall, cleared 
of all supports in five days from the time of filling 
in; but this was with good cement, gauged 1 part to 2 
of aggregate, and in warm weather, and the stair was 
strengthened with T iron. 



406 CEMENTS AND CONCRETES 

The centring and framing for a flight of stairs should, 
where practicable, be independent of other stairs above 
or below, so that they can be struck in due rotation. 
The wedges of the main props should be gradually 
withdrawn. This tends to avoid the sudden jar which 
otherwise often happens when the centring is too sud- 
denly struck. The sudden removal of centring and 
the inflexible nature of concrete are the cause of body 
cracks. The damage caused by the sudden jar may 
not be seen at the time, but it will be eventually devel- 
oped by the force of expansion, which always finds out 
the weak spots. 

Concrete and Iron. — Iron pipes, bars and" T pieces 
are sometimes used with concrete stairs where the steps 
are long, or Avhere landings have little support from 
walls. They help to carry the dead weight until the 
mass is thoroughly set, and also prevent sudden de- 
flection if the centring is struck too soon. When iron 
pipes are used for steps they should go right into the 
wall chase. Iron T pieces are used for long landings. 
Care must be taken that, if the iron is used, no part 
should be left exposed. It must be embedded in the 
concrete to protect it from oxidization and the effects 
of fire. When iron girders, etc., are partly exposed, 
.they should be painted. Iron bars or pipes are occa- 
sionally used to strengthen the outer strings of spandrel 
stairs. The iron is laid in the moist concrete 
near and along the string, having the ends projecting 
into the walls or landings. Angle irons are often used 
for unsupported concrete angles. Iron pipes, bars or 
joists are used as integral supports for landings and 
floors having unsupported ends. 

The tensile strength of bar iron is materially in- 



HOW TO USE THEM 407 

creased by twisting. A bar % inch square with three 
twists per foot will gain about 50 per cent, in tensile 
strength when embedded in concrete, and give a corre- 
sponding strength to the concrete. A combination of 
iron and concrete is of special service where space is 
limited. For instance, if a beam or landing requires 
a certain thickness to carry a given weight, and it is 
inconvenient or difficult to obtain that thickness, the 
requisite degree of strength with a reduced thickness 
may be obtained by the combination of both materials. 
This gives the combined iron and concrete a useful ad- 
vantage over stone. It is important to secure the full 
strength of the iron, and that none be lost or neutral- 
ized. In order to obtain the full strength the iron 
should be judiciously placed. Thus, a piece of iron 
surrounded by twenty times its sectional area of con- 
crete would increase the weight-sustaining power of the 
iron in the centre and would have its strength in- 
creased about twice. If the same quantity of iron was 
placed in several pieces, so as to throw as much tensile 
strain on the iron as possible, the strength would be 
increased nearly four times. In order that none of the 
strength be lost or neutralized, the iron should be 
placed near the lower surface ; if fixed higher, they are 
nearer the axis of neutral stress, and are correspond- 
ingly less effective. The use of iron in concrete is in- 
valuable for many constructive purposes, but for gen- 
eral work, unless as a temporary aid and in a few ex- 
ceptional cases, it is unnecessary. For all other things 
being equal, the huge board of reserve strength in good 
concrete is alone sufficient to sustain as great if not 
a greater Aveight than that sustained by natural stone. 
No other artificial compound exceeds the strength of the 



408 CEMENTS AND CONCRETES 

natural substance, as does artificial stone composed of 
Portland cement concrete. 

Setting Concrete Soffits. — The soffits of stairs and 
landings, if neat cement has been used on a water- 
proof centring, as already described, only require a lit- 
tle stopping and coloring, but for work done on rough 
centring a setting coat has to be laid. This is usually 
done Avith neat Portland cement, though it is frequently 
gauged with lime putty to make it work more freely. 
The surface should be well roughened and wetted, to 
give a key and obtain perfect cohesion. It requires 
great care and time to make a good and true surface 
with Portland cement on a body of concrete, espe- 
cially if the concrete is dry, which is generally the 
case where there are several flights of steps in a stair- 
case, and the setting of the soffits and landings are 
left to the last part of the work. I have obtained 
equally good results by using Parian or other white 
cements for setting the soffits of staircases. When 
using w^hite cements for this purpose it is better to 
brush the concrete surface with liquid cement before 
laying the gauged cement. The laying trowel should 
follow the brush, or at least before the liquid cement 
dries in. This not only secures better cohesion, but 
tends to prevent the setting coat peeling when trowel- 
ling it off. Soffits are sometimes set with gauged put- 
ty. This is like putting a beggar on horseback, and 
the work is never satisfactory. 

Fibrous Concrete. — As already mentioned, canvas 
and other fibrous materials may be advantageously 
used with Portland cement for several purposes. Can- 
vas forms a good ground for a setting coat on concrete 
surfaces. It gives a uniform and strong key, prevents 



HOW TO USE THEM 409 

surface cracks, and the final coat from peeling. Coarse 
canvas cut to convenient sizes is used. It is laid on 
the centring, and held in position with tacks, or v\^ith 
the same kind of cement as intended for the final coat. 
The canvas is then brushed with liquid cement, and 
then the concrete is laid while the canvas is moist, so 
that the whole will form one compact body. When the 
centring is struck, the fibrous concrete surface is rough- 
ened with a sharp and fine drag, so as to raise the 
fibre of the canvas, thus giving a fine, regular and 
strong key. This surface requires less material for the 
final coat than the ordinary concrete surface. If tacks 
are used they must be extracted before the final coat is 
laid, to avoid discoloration. The rough concrete and 
the white surface coat may also be done in one opera- 
tion. The centring is made fair and smooth, and then 
oiled with chalk oil. The white cement is gauged stiff 
and laid on the centring. Coarse canvas is then laid 
on and well brushed with liquid cement. When this 
is firm (but not set) the surface is again brushed, 
and then the concrete is laid. The concrete is deposited 
in two or more layers. The first must not be too thick, 
taking care that it is well rammed or pressed on the 
moist canvas surface without disturbing the white ce- 
ment. After the centring is struck any defects on 
the surface are made good. The surface may be then 
left white, or painted, or polished as required. 

Polished Soffits. — -Soffits, landings and strings of con- 
crete stairs that are finished in white cement may be 
polished. The material may be tinted, or left in its 
natural white or creamy color. Polished cement work 
is always bright and has a lustre like marble. Tap- 
ing durable and easily cleaned, it is more sanitary and 



410 CEMENTS AXD COXCRETES 

cheaper than paint. The polishing is done the same 
way as described for 'Syhite work." 

Concrete Staircases and Fihrous Plaster. — Fibrous 
plaster is Avell adapted for concrete surfaces when an 
enriched finish is desirable. I have introduced this 
material for deeoratino' the soffits of steps and land- 
ings : also the strings of concrete stairs. By this method 
the soffits mav also be enriched, and strins's can be 
panelled, or enriched with medallions or foliage, as re- 
quired. The soffits may also be enriched with modelled 
work done in situ, with some of the white cements, or 
with plaster and tow. The strings may be decorated 
with hand-wrought gesso. In order to obtain a fijKing 
or keving substance that will receive nails or screws 
to sustain the fibrous plaster, a rough plan of the de- 
sign, or rather the fixing points, is set out on the in- 
side of the centring before the concrete is laid. On 
these plans wood plugs, fillets or concrete fixing blocks 
are laid, and held in position with nails, plaster or ce- 
ment until the concrete is laid and set. Care must be 
exercised when fixing the plugs or fillets that the 
centring will leave freely without disturbing the plugs, 
etc. 

Dowel Holes. — Cutting dowel holes in concrete to 
receive iron or wood balusters is a slow -and tedious 
process. They are best formed by means of wooden 
plugs, which are fixed before treads; the plugs are 
driven into the rough concrete before it is set, leaving 
them flush with the line of tread, so that when the 
topping is laid they will not be in the way. Plugs 
are best fixed by the aid of a wooden gauge. The 
gauge is made the same thickness as the topping, the 
length being equal to the distance between the nosing 



HOW TO USE THEM 411 

mould and the riser board, and as wide as will admit 
of plug holes and the plugs to be driven through. The 
plugs are made a little larger than the baluster ends 
to allow for the lead. The gauge is laid on the rough 
concrete, using the returned nosing as a guide, and then 
driving the plugs flush with the top of the gauge. 
The gauge is then lifted up and laid on the next step, 
and so on until the finish. This method is accurate 
and saves measuring and marking the position of each 
hole on every step. When balusters are fixed on the 
ends of the steps, the plugs are fixed on the inside of 
the outer string. The plugs are generally left in until 
the balusters are ready for fixing. A ready method 
for forming "lewis" holes or other undercut sink- 
ings in concrete is performed by casting wedge-shaped 
blocks of plaster of the required form and size, and 
then laying them in the desired positions while the 
concrete is soft. When the concrete is set, the plaster 
blocks can then be easily cut out, leaving the under- 
cut sinking as desired. 

Summary of Staircases Constructed ^'in Situ.^^ — It 
will be seen from the foregoing that the operations em- 
ployed in the construction of concrete staircases formed 
m situ are: (1) setting out the stairs and landing; (2) 
fixing the wood framing; (3) gauging the materials and 
filling in; (4) removing the framing; (5) cleaning up 
the treads, risers and strings; (6) striking the soffit 
centring and finishing the soffits; (7) protecting and 
wetting the work until set and hard. 

Cast Steps. — Staircases are also constructed with 
steps cast separately, and then built in, in the same way 
as stone. Illustration No. 24 shows various sections 
of steps. Fig. 1 is a spandrel step, which may be used 



412 



CEMENTS AND CONCRETES 



for model dwellings, factories, etc. The tread is grooved 
to afford a good footing and prevent dipping. The 
dotted line indicates a square seating or tail-end of the 
step, which is embedded in the wall. Fig. 2 is a square 
I step. Fig. 3 is a step with a moulded and returned 



Fig. I. 




••«••»••*• •• 



Fig. 2. 



Fig. 3. 



Fig. 4. 




Sections of Steps. 

NO. 24. 



nosmg 



Fig. 4 is a similar step, but having a moulded 
soffit. For cast work these steps must have a square 
seating or tail-end, as indicated by the dotted lines on 
1, so as to bond into the wall. 



Fig 




Treads and Risers. 

NO. 25 

Treads and Risers. — Stairs between walls are some- 
times formed with treads and risers. The treads and 
risers are cast and built in as the construction of the 
work proceeds. Sometimes they are let into chases and 
pinned after the walls are built. Illustration No. 25 
shows a section of treads and risers. 



HOW TO USE THEM 



413 



Closed Outer Strings. — Staircases are sometimes fin- 
ished with a close outer string, which prevents dirt or 
wet falling into the well. Illustration No. 26 shows 
the section, Fig. 1, and the elevation, Fig. 2, of a 
moulding outer string. The dotted line at A indicates 
a dowel hole for the balusters. Outer strings, whether 
plain or moulded, are much stronger when formed in 





Fig; I. 

NO. 26. 



Fig. 2. 



situ. This is best effected by fixing a reverse mould 
at each side, then filling in the space from the top. The 
top is finished by hand and the aid of a template. The 
dowel holes are formed as already described. 

Concrete Floors. — It has been mentioned that the 
Romans, in the time of Julius Caesar, were in the habit 
of constructing their floors and roofs, as well as their 
walls, of concrete. According to an article in Archaeolo- 
gia, the cementitious agent was pozzolana. The lime 



414 CEMENTS AND CONCRETES 

was obtained by burning ^'traverstine." The aggregate 
usually consisted of broken tufa for walls, of broken 
lava for foundations where great strength was re- 
quired, and of broken pumice where lightness was es- 
sential. The floors were generally constructed of large 
slabs of concrete, supported on sleeper brick walls. 
The upper surface was finished with a layer of finer 
concrete and mosaic. The roofs were made flat, rest- 
ing on brick pillars. The first known English patent 
fireproof construction was obtained by one Dekins Bull, 
in 1633 ; but as at that period patentees were not com- 
pelled to disclose what their patents covered, no de- 
scription of the materials and methods can be given. 
Up to the middle of the eighteenth century fireproof 
their great weight and cost, were seldom used. But 
towards the close of that century cast-iron girders and 
segmental brick arches were gradually coming into use 
where strength was essential. Up to a century ago 
plaster was largely employed as a floor material. In 
floors usually consisted of brick arches, but owing to 
1778 Earl Stanhope invented pugging for rendering 
wooden floors fireproof. By this process fillets were 
X)aled to the joists at about one-third of the heightc 
Laths were laid on the fillets and plastered above and 
below with a coat of lime and chopped hay. The under 
sides of the joists were then lathed and plastered in the 
usual way to form the ceiling. About the early part of 
the last century wrought iron joists were substituted 
for cast iron girders. Fox & Barret's floor, designed 
about 1830, was the first in which an attempt was nrnde 
to protect the exposed faces of the iron joists with a 
fire-resisting material. Hornblower's floor is one of the 
earliest for resisting the effects of fire. Iron, bricks 



now TO USE THEM 415 

and plaster are chiefly nsed in the French and Ameri- 
can systems. For the sake of simplicity and reference, 
concrete floors may be divided into three kinds: (1) 
^•' Joist floors," in which the concrete is laid slid be- 
tween the joists; (2) ''Tabular floors," formed with 
fireclay tubes or hollow lintels placed between the 
joists and covered with concrete; (3) "Slab floors," 
formed in one piece or slab. Portland cement concrete 
laid in situ on and between iron joists is extensively 
used for fire-resisting structures. Cast concrete is used 
for some parts of tabular fioors. Cast concrete blocks 
are used for the ceiling surface, and as a support for 
the rough concrete floor surface. The' blocks are hol- 
low, and have male and female dovetails on the sides» 
The ceiling surface of the floors and the outer surfaces 
of the partitions are finished with a thin setting coat of 
gauged putty or Parian. The chief objects of fire- 
proof floors are to render each floor capable of resist- 
ing the effects of fire, so that fire cannot be communi- 
cated from one floor to another, and by making the 
roof fireproof, to prevent the fire from spreading from 
one compartment to another; to gain additional 
strength, so as to avoid as far as possible lateral thrust 
on the walls, and to secure the building from attacks 
and effects of both dry rot and damp. There have been 
about a hundred patents for fireproof floors during the 
past generation, of which about five or six survive. 

Plaster Floors. — Plaster concrete, that is, plaster and 
broken bricks, or similar aggregates, also neat plaster, 
were at one time used largely for the formation of 
floors. The use of plaster floors was common in some 
districts, and up to a century ago the rough plaster, 
known as "floor plaster," was in general use where 



416 CEMENTS AND CONCRETES 

gypsum was found in abundance. Plaster floors were 
rarely used on tlie ground level, because tliey could not 
resist moisture, which caused them to become soft and 
retain the damp. They were principally used for up- 
per floors. The gauged plaster was laid upon reeds. 
These reeds were spread upon the tops of joists, and 
over them was laid straw to keep the soft plaster from 
percolating through the reeds. The floors were about 
3 inches thick, floated fair, and finished the following 
day. Wood strips were placed aroimd the walls, and 
drawn out when the plaster began to set, to allow for 
ihe expansion of the plaster. The materials being so 
light, the timbers were less in size and number than 
those now in use. The joists were in some instances 
3% inches by 2% inches, fixed wide apart, and sup- 
ported by small beams about 4% inches by 3% inches. 
The undersides between the joists were made fair by 
plastering the reeds, but in the better class of work the 
joists were covered with reeds, and held in position with 
oak laths, and plastered. Bullock's blood was used to 
harden the floors after thev were drv. In some in^ 
stances they were coated with linseed oil to increase 
their hardness. Their use is now practically super- 
seded by Portland cement concrete. 

Joist Concrete Floors. — For this form of floor the 
concrete is laid between, over and under the iron joists 
Beyond the supervision of the fixing of the centring 
and the gauging of the materials, little skilled labor is 
required. The rough concrete is laid between and 
partly under the iron joists, which are fixed from 3 feet 
to 5 feet apart, according to the span and strength of 
the joi-sts. The centring is supported, or rather hung, 
by the aid of timber laid across the joists and secured 



HOW TO USE THEM , 417 

by bolts. The materials are generally Portland ce- 
ment and gravel, coke-breeze, clinkers and broken 
bricks, gauged in the proportion of 1 part of matrix 
to 5 of aggregate. Sand eqnal to one-third of the 
bulk should be added. Coke-breeze is weak, light and 
elastic, but combustible and porous. A mixture of 
gravel and breeze in equal proportions is better than 
either alone. The proportion of cement varies accord- 
ing to the span and class of aggregate. All other 
things being equal, the strength of concrete is influ- 
enced by the strength of the aggregate, so that it 
would take a greater proportion of cement to make 
coke-breeze concrete equal in strength to a concrete 
made with hard aggregate, such as granite, slag or 
brick. The upper surface of this class of floor may 
be finished with wood, tiles or fine concrete, as re- 
quired. Joist concrete floors have been largely used. 
This is principally owing to their supposed cheap- 
ness, but it is more than probable that, in the event 
of fire, they would be dear in the end, because the 
lower part of the flanges are barely protected from the 
effects of fire, as the concrete, being thin at these parts, 
and also on a comparatively smooth surface, would 
soon crack or scale off, and leave the flanges of the 
joists exposed to the ravages of fire. They are also 
more or less conductors of sound. Caminus concrete 
cement is an excellent material for the construction 
of fireproof ceilings and partitions. 

Caminus Concrete Cement. — This material is specially 
designed to produce a hard and practically indestructi- 
ble concrete for the construction of fireproof floors and 
walls. It is manufactured from a waste product, and 
all inflammable material, such as coke-breeze, being en- 



418 , CEMENTS AND CONCRETES 

tirely dispensed with, the concrete is thoroughly fire- 
resisting. It is lighter and much cheaper than Port- 
land cement concrete, and is perfectly free from ex- 
pansion and contraction whilst setting. It can be man- 
ufactured to set in a few hours, so that the centres 
can be struck the day after the floor is laid. It can 
be supplied in a ready aggregated condition, so that the 
bags may be hoisted direct to the floor where the con- 
crete is being laid, and gauged on the floor, thus sav- 
ing a great amount of waste, and also labor in handling, 
mixing and laying. 

Concrete Floors and Coffered Ceilings. — A method 
was patented by E. Ransom for decreasing quantity of 
material and yet obtaining equal strength in floors. The 
floor is divided by a series of beams at right angles 
to each other, so as to form a series of coffers in the 
ceiling. For instance, for a floor 12 inches thick, the 
floor proper w^ould be about 4 inches thick, and beams 
about 3 inches thick and 8 inches deep — a rod of twist- 
ed iron being placed in the centre of the thickness, and 
near the lower surface of the beams. The beams are 
generally about 2 feet 6 inches from centre to centre. 
The method of construction is as follows : First, form 
a platform or centring; on this a series of core boxes 
2 feet 3 inches is placed, 3 inches apart, so as to form 
a 3-inch beam. The core boxes must be tapered and 
their upper edges rounded, so that they will draw when 
the centring is struck. The size of the core boxes may 
be altered to suit the size and requirements of the 
floor. With regard to the iron bars, the inventor says : 
*'It is of vital importance for the strength of the struc- 
ture that the iron bars be placed no higher in the beam 
than calculated for; that the longitudinal centre of 



HOW TO USE THEM 419 

these bars should be at the lowest point; and it is ad- 
visable that the bars curve upwards slightly and uni- 
formly each way from the centre to the ends, so that 
the ends are from 1 to 3 inches higher than the cen- 
tres. By preparing the concrete bed on a correspond- 
ing curve, the natural sag of the bar, as it is being 
handled to its place, gives all the requisite facility to 
accomplish this purpose. No crooked or irregular 
twisted iron must be used; otherwise, when the strain 
comes upon it, it will perforce straighten and lengthen 
out, and weaken the structure in so doing. After 
placing the iron, the rest of the concrete is tamped in 
place, and the whole made to form a monolithic block. 
It is of vital importance that no stop be made in the 
placing of concrete from the time the beam is begun 
until the thickness of the beam is in place and a 
'through joint' is made. The web and the thickness 
must be one solid piece of homogeneous concrete." 

Combined Concrete Floors and Panelled Ceilings. — A 
combined floor and panelled ceiling may also be formed 
in concrete. This is executed as follows: First, form 
a level platform or centring, and on this fix the re- 
verse plaster mould, run and mitred, according to the 
design of the ceiling. The intervening panels are then 
made up with framing, and the concrete filled in the 
usual way, and when set the centring and reverse 
mould are removed, and the ceiling cleared off. If de- 
sired, a finely finished and smooth white surface may 
be obtained by coating the surface of the moulds and 
panels with firmly gauged Parian, or other white ce- 
ment, until about % inch thick, and when this is firm 
(but not set), the rough concrete is deposited in layers 
and tamped to consolidate the concrete, and unite it 



420 CEMENTS AND CONCRETES 

witli the white cement. The surface may also be fin- 
ished with fibrous concrete. The method of doing this, 
also for carrying out the above white cement process, is 
described in "Fibrous Concrete." 

Concrete and Wood. — Concrete floors finished with 
flooring boards require special care to prevent damp or 
dry rot. There are various methods in use for fixing 
and keeping the flooring boards from contact with the 
rough concrete, one way being to fix wood fillets to the 
joists by means of w^edges or clamps. Another way 
is to embed wood fillets or fixing blocks in the rough 
concrete, leaving them projecting above the level of the 
iron joists, to give a bearing and fixing points to the 
flooring boards; or fine coke-breeze, concrete or plas- 
ter screeds, may be laid at intervals on the rough 
concrete, onto which the boards are nailed. Fixing 
blocks, concrete or plaster screeds, are preferable to 
wood fillets, as they do not shrink or rot, and will 
better resist fire. All these methods leave intervening 
spaces between the concrete and the boards, and unless 
thoroughly ventilated, they harbor vermin, dirt and 
stagnant air. Unless the wood is thoroughly seasoned, 
and the boards grooved and tongued, dust and ef- 
fluvia will find egress through the joints. A portion of 
dust and water when sweeping and washing the floors 
also finds egress through the joists; and as the concrete 
will not absorb the water, or allow the dust to escape, 
they accumulate and become unseen dangers. These 
sanitary evils may be obviated, or at least reduced to 
a minimum, by laying the boards direct on the con- 
crete. This not only forms a solid floor with no inter- 
spaces, but admits of thin boards being used with as 
much if not greater advantage than a thick board. 



HOW TO USE THEM 421 

There is no uneven springing between the joists, which 
causes friction and opening of the joints, and the whole 
thickness is available for wear. There is also less total 
depth of floor, consequently less height of building and 
general cost. Another important advantage of a solid 
floor is that it will resist fire better than one with hol- 
low spaces. It is here that the sponginess and elasticity 
of coke-breeze concrete as a top layer is of special 
service, and where it may be utilized with advantage. 
Owing to its being able to receive and retain nails, the 
boards can be nailed at any desired place. Wood 
blocks for parquet floors can also be bedded or screwed 
on the concrete surface. Flooring boards will lie even 
and solid on this surface, and if a thin laver of felt or 
slag-wool be spread on the concrete before the boards 
are laid, a firm and noiseless floor is obtained. Slag- 
wool is an imperishable non-conductor of heat, cold 
and sound, and it will not harbor vermin. If the work 
is in humid climate, the coke-breeze surface when dry 
should be coated with a solution of tar and pitch, to 
prevent atmospheric moisture being absorbed by the 
porous coke-breeze. 

Concrete Drying. — To prevent dry rot It is of the ut- 
most importance that the concrete should be thoroughly 
free from moisture before the flooring boards are laid 
and fixed. The drying of concrete is a question of 
time, which depends upon the amount of water used 
for gauging, the thickness and the temperature. It 
may take from three days to three weeks or even three 
months. The drying can be accelerated by directing 
currents of hot air on the lower surface, or by laying 
some absorbent material, such as dry sawdust or brick 
dust, on the upper surface. As soon as the surface 



422 CEMENTS AND CONCRETES 

moisture is absorbed, or the dry material has no further 
absorbent power, it should be removed to allow the 
mass to be air dried. Another way is to la}^ the floor 
in two coats, and to allow one coat to dri^ before the 
other is laid. For instance, if the floor is to be 6 
inches thick^ the first coat is laid with rough, but 
strong concrete, the aggregate being the best available ; 
but taking gravel and coke-breeze to be the most 
plentiful, it will be best to assimilate and combine the 
good qualities of each to equalize their defects by mix- 
ing them in equal proportions. If brick is plentiful, 
and broken to properly graduated sizes, it will give 
better results than gravel or breeze. The mixed ag- 
gregate is gauged 5 parts to 1 of cement, and laid 4% 
inches thick, and gently but firmly beaten in situ, the 
surface being left rough to give a key for the second 
coat. The second coat is not laid until the first is 
dry, and consists of one part cement to 5 of sifted and 
damped coke-breeze, gauged stiff, and laid 1% inches 
thick, beaten in situ, ruled level, and any ridges being 
laid fair with a long hand-float. The moisture of the 
second coat, by reason of the density of the first coat, 
will only be absorbed to a small degree, while the 
greater portion will be taken up by the atmosphere, 
and enable the combined coats to dry sooner than if 
laid in one. The first coat should be laid as soon 
as the roof is on, so as to give all possible time for it 
to dry, and the second coat to be laid and dried before 
the flooring is laid. When coke-breeze is not avail- 
able for the second coat, use soft brick, broken to pass 
through a 3-16-inch sieve. The method of laying floors 
in two coats is only given as an alternative plan, and 
as an example of a process used in some parts. Greater 



HOW TO USE THEM 423 

strength, as a whole, and more perfect cohesion be- 
tween the two coats, is obtained by laying the second 
coat as soon as the first is laid, or at least while it is 
green. 

Concrete Slab Floors. — The term, slab floor, is applied 
to a concrete floor formed in situ, and in one piece or 
slab. It must not be confounded with slab pavements, 
which are constructed with a number of small cast 
slabs. Slab floors are usually made without exterior 
iron supports, but in a few instances iron T pieces or 
bars have been used as internal supports. Bearing in 
mind the lasting properties of the old Roman slab 
floors, and the enormous strength of the modern exam- 
ples at home, which are unsupported by iron, and are 
practically indestructible, it seems strange that they are 
not in more general use, and that for some inexplica- 
ble reason preference is given to shrinking, rotting 
and combustible floors^ composed of poor iron and tim- 
ber instead of the best work and material, which, if a lit- 
tle dearer at first, is infinitely superior and vastly 
cheaper in the long run. The great sanitary advan- 
tages and fire and damp resisting powers of concrete 
slab floors are the highest known. The construction of 
slab floors is simple, and similar in many respects to 
that already described for stair landings and ordinary 
concrete and joist floors. There are several methods 
of supporting the floors, the first and most common 
being to leave a sand course or to cut a horizontal chase 
in the walls to receive the ends of the floors. The 
second is to lay the floors when the walls are floor 
high, and build the higher walls on it when set. This 
method, while making sound work, is not always prac- 
ticable or convenient, owing to the delay in building 



424 CEMENTS AND CONCRETES 

while waiting for tlie floors to set. The third method 
is to build corbelled ledges in the walls, so as to carry 
the floors. The centring for slab floors should be per- 
tectly rigid, water-tight and slightly cambered towards 
the ceiling centre. This camber gives more strength 
to the floor, and lessens liability to crack when remov- 
ing the centring. If joists are not used, the centring 
is supported on Avail boards and centre struts, i^- 
other way which gives great additional strength is to 
form the centring level, but having all the edges at the 
wall rounded off, so as to form the floor like an in- 
verted sink or tray. The horizontal chases in this case 
should be made wider than the thickness of the floor to 
allow for a thickness of rim. The extra width of chase, 
which may be one or two bricks thick, according to the 
width of span, is made below the centring or line of 
ceiling, the angles being coved by rounding the edges 
of centring. The coved rim gives greater strength 
with a less thickness of floor. The cove may be left 
plain or used for a cove for a plaster cornice, or rough- 
ened and used as a bracket for the same purpose. The 
expansion of concrete floors having large areas, or 
where hot cement has been used, has been known to 
disturb the walls^ causing cracks and displacement of 
brick and stone work. This may be prevented by 
isolating the floor ends from the walls. This is done 
by forming expansion partitions or linings in the chases, 
the linings being composed of slag, felt or wood shav- 
ings, straw, reeds or other compressible material. The 
chase should be sufflciently deep to allow for a com- 
pressible lining about IV2 inches thick, and a fair bed 
for the slab floor. Care must be taken to leave a few 
half bricks solid at intervals, say from 3 to 4 feet 



HOW TO USE THEM 425 

apart; to support the upper walls until the floor is set. 
Compressible linings may be used for floors supported 
on corbelled ledges; and when the expansion, and in 
many cases subsequent contraction, has finally finished, 
the linings can be taken out, and the vacant space 
filled up with fine concrete, or utilized as a ground key 
for cement skirtings. If girder or iron posts are iso- 
lated from the walls by means of compressible linings, 
the effects of expansion and sound are limited. In 
some instances a judicious use of iron may be made. 
For instance, large areas may be divided with three or 
four rolled iron joists, so as to form shorter spans or 
smaller bays. Joists tend to bind the walls together, 
and to serve as scaffold bearings for building the upper 
parts of walls. They may also be used for hanging 
the centring on instead of strutting, or as aids to the 
strutting. Joists may also be used as integral sup- 
ports at unsupported ends of concrete floors. They 
should be so fixed that the lower flanges are not less 
than 1 inch above the lower surface of the concrete. 
The whole strength of iron is brought more fully into 
use hy fixing it near the lower surface. If fixed near 
the centre, or at the axis of neutral stress, a correspond- 
ing part of the strength is comparatively of little 
value„ 

Construction of Slab Floors. — Portland cement as a 
matrix is indispensable. The unequal nature of gravel 
and coke-breeze renders them unfit and unsafe aggre- 
gates for this class of work. Broken brick being cheap, 
and obtainable in most districts, affords a ready aggre- 
gate, and may be used with safety and success. In 
ordinary cases of concrete construction, the whole 
thickness is usually made with one rate of gauge; but 



426 CEMENTS AND CONCRETES 

for slab floors covering large areas, and unsupported 
by iron or other supports, exceptional strength is re- 
quired. Stronger results are obtained by making up 
the whole thickness with different rates of gauge. Tak- 
ing the usual gauge for floors as from 4 to 5 parts of 
aggregate to one of cement, and used for the whole 
thickness, it gives an unequal strength, a part of which 
is comparatively of little use, especially at the neutral 
axis ; but if the cement is divided so as to form an 
ordinary coat in the centre, and stronger coats at the 
upper and lower surfaces at the points of greatest 
strain, the upper being compressive and the lower ten- 
sive, a better and more accurate arrangement of 
strength and allowance for disposition of strains is ob- 
tained. The additional strength at the proper places 
is obtained not only by the use of additional cement, 
but by the method of construction, which enables the 
same quantity of cement as gauged for the usual rate 
for forming the whole thickness in one coat to 
be used more profitably. Take the section of 
an iron joist as an example; this gives divided 
yet united strength, which sounds paradoxical, 
but is true. The flanges sustain the greatest 
strains, and the web comparatively little. With con- 
crete, the strong coats at the upper and lower surfaces 
represent the flanges, and the ordinary coat the web. 
As already stated, the increased and profitable dis- 
tribution of strength is obtained by the method of con- 
struction. For instance, take a slab floor 20 feet by 
14 feet and 12 inches thick^ without iron joists or other 
supports, and intended to carry a safe load of 2% cwt. 
per superficial foot, in addition to its own weight of say 
1 cwt. per square foot. This floor is laid in three coats, 



HOW TO USE THEM 427 

the first composed of 1 part cement and 2 of fine broken 
bricks gauged stiff, and laid 2 inches thick ; the second 
composed of 1 part cement and 6 of coarse broken 
bricks gauged stiff and laid and rammed 8 inches thick ; 
and the third composed of 1 part cement and 2 of fine 
broken bricks gauged stiff and laid 2 inches thick. 
If the upper surface is intended for hard frictional wear 
a slight difference is made in the gauge and materials. 
The first coat is composed of 2 parts of cement and 5 of 
fine broken bricks gauged stiff and laid 2 inches thick ; 
the second of 1 part cement and 6 of coarse broken 
bricks gauged stiff and laid and rammed till 8 inches 
thick ; and the third coat composed of 1 part cement and 
2 of fine crushed slag or granite. It will be seen that 
this constructive method gives the desired positions of 
strength, and the total quantity of cement in the united 
gauges is 1 part to 4, and up to 5 parts of aggregate. 
The fine broken bricks should be passed through a %- 
inch sieve, and the coarse through a 2-inch screen, 
taking care that the latter contains a greater quantity 
of the smaller pieces than of the larger. It must be 
clearly understood that the second coat must be laid 
before the first is set; also that the third is laid before 
the second is set, so as to ensure perfect cohesion be- 
tween each coat^ and the absolute homogeneity of the 
whole mass. 

Hollow Floors. — Greater lightness in concrete floors is 
obtained by the use of concrete tubes. If the tubes are 
placed apart and in the centre of the floor thickness, 
a hollow homogeneous concrete slab is formed. The 
vertical divisions between the tubes connect the upper 
and lower coats^ as with a web of a joist connecting the 
upper and lower flanges. The method of construction 



428 CEMENTS AND COXCRETES 

is simple and expeditious. For example, for a slab 
floor 10 inches thick, first lay a coat 2 inches thick of 
the stronger and finer concrete, as described for the 
12-inch slab floor, and when this is firm lay 5 or 6- 
inch tubes from wall to wall. Bed the sides with rough 
concrete, and lay another row of tubes parallel with the 
first row and about 2 inches apart, and so on until the 
floor area is covered; then make up interspaces with 
rough concrete till level with the upper surfaces of the 
tubes, and then cover this with a coat of fine concrete 2 
inches thick. Concrete tubes or common earthenware 
drain pipes may be used. Half-circle pipes, laid on 
their side edges, may be used to save concrete and 
weight in joist floors, etc. 

Concrete Roofs. — Concrete roofs require special care 
to render them watertight. Subsidence in the brick 
work of new buildings is often the cause of cracks on 
concrete roofs. The roof should have a good camber, 
to give greater strength and allow for the fall of wa- 
ter to the outer edges. The rough coat should be laid 
and well consolidated by ramming or beating, and then 
left for seven days (the longer the better) before the 
topping is added. The upper coat should be strongly 
gauged with fine aggregate, as in ''Eureka." If possi- 
ble, the topping should be laid in one piece. If the 
area is too large to be laid and finished in one piece, 
the joints of the bays should overlap. This is done 
by rebating the screed rules, so as to allow one-half of 
topping thickness to go under a part of the rule and 
form an underlap or ledge about !/:> inch wide, and 
when the adjoining bay is laid an overlapped but level 
joint is the result. Roofs exposed to the sun's heat 
should be kept damp for several days after being laid, 



HOW TO USE THEM 429 

as joints are affected by the heat as well as by deflec- 
tion of centring or subsidence of walls. Compressible 
linings or wood strips should be used round the walls 
to counteract any expansion. All concrete roofs should 
have a cement skirting 6 inches high and 1 inch thick 
well keyed into the walls. It linings are not used when 
the topping is laid, the topping should be turned up on 
the walls, so as to form a rim, to prevent water get- 
ting between the roof and the walls. Greater heat and 
damp-resisting powers are obtained by laying the up- 
per surface with %-inch thick coat of special concrete, 
composed of 1 part of Portland cement, % part of 
slaked lime and 1 part of firebrick dust. This should 
be consolidated with a hand-float, and finished fine and 
close with a trowel. 

Notes on Concrete. — When calculating the strength of 
floors, stairs, etc., the following facts should be borne 
in mind : Portland cement, when new, is too hot ; sets 
more rapidly and expands more than oLi cement. The 
finest ground cement is the best and strongest. The 
time in setting, and in which the maximum strength is 
attained, varies according to the age of the cement, the 
quantity of water used, and the mode of gauging and 
the mean atmospheric temperature. The maximum 
strength of a briquette of mature cement is maintained, 
while one of new cement ^'goes back." A briquette of 
matured cement will stand a tension sj^rain of 550 
pounds per square inch, and a crushing weight of 6,000 
pounds per square inch. A briquette of neat cement is 
more brittle than one of concrete. Briquettes mature 
more rapidly than thick slab floors. The adhesive 
strength of Portland cement is about 85 pounds per 
square inch. The adhesive strength increases more 



430 CEMENTS AND CONCRETES 

rapidly than the cohesive. A mass with a surface 
large in proportion to its volume sets more rapidly than 
a mass with a small area in proportion to its volume. 
Masses subject to pressure set more rapidly and attain 
greater hardness than masses not so pressed. The 
average compressive strength of concrete is about eight 
times its tension strength. The proportion of com- 
pressional and tensional strength varies according to 
the quality and quantity of the aggregate. The strength 
of concrete depends greatly on the proportion of the 
matrix and aggregate; also on the strength of the lat- 
ter. As regards bricks, it must be remembered that 
there is a wide difference between the tensile strength 
of hard, well-burnt bricks and soft stocks. No bricks 
are so strong as cement, the best kinds being about 
one-fourth the strength of neat cement. Taking the 
gauge as one part of cement to 4 of broken brick, the 
strength of the concrete will be about two-fifths of neat 
cement, but for safe and practical calculations it v/ili 
be best to take the strength as one-fourth of neat ce- 
ment. Square slabs are stronger than rectangular 
slabs. Slab floors being homogeneous throughout, the 
whole weight is a dead weight, and consequently there 
is no thrust on the walls. With regard to the live load 
or weight which fl.oors should be constructed to carry, 
some difference of opinion exists. Hurst says that for 
dwellings 1^/4 cwt., public buildings % cwt. and ware- 
houses and factories 2^^ cwt. are safe calculations. 
Others assert that for domestic buildings 1 cwt. per foot 
would be ample for all contingencies. An American 
authority states 40 lbs. is sufficient for ordinary pur- 
poses. The following table shows the results of tests 



HOW TO USE THEM 



431 



of slab floors made without iron. The slabs were sup- 
ported all round, and uniformly loaded with bricks. 



Test of Slab Floors. 



No. 


Length 
between 
Sup- 
ports, 
feet. 


Breadth 
between 
Sup- 
ports, 
feet. 


Thick- 
ness, 
feet. 


Age in 
Days. 


Breaking 

Weight, in 

cwt. per 

sq. ft. 


Weight of 

Slab, in 

cwt. per 

sq. ft. 


Total 
Breaking 
Weight, in 
cwt. per 

sq. ft. 


1 


14.5 


6.75 


.5 


7 


3. 


.54 


3.54 


2 




u 




14 


2.76 




3.30 


3 




<< 




21 


8.88 




9.42 


4 




13.5 




7 


1.07 




1.61 


5 




6.75 




14 


2.51 




3.05 


6 




(( 




21 


2.84 




3.38 



Cast Concrete. — Innumerable patents have been ob- 
tained for a combination of materials, also moulds for 
the construction of artificial stone. Among the many 
that may be mentioned is Mr. Ranger's system. He 
obtained a patent in 1832 for artificial stone formed 
with a lime concrete. The aggregate consisted of 
shingle, broken flints, mason's chippings, &c. The in- 
ventor stated that the best results were obtained by 
using 30 lbs. of an aggregate of a siliceous or other 
hard nature, 3 lbs. powdered lime, and 18 ozs. boiling 
water. No more of the materials were gauged at the 
time than were sufficient to fill one mould, as the boil- 
ing water caused the concrete to set very rapidly. This 
material, after fifty years' exposure is still sound and 
shows no sign of decay. No artificial stone equals, far 
less excels, the strength and durability, sharpness, and 
evenness of Portland cement concrete. This form of 
artificial stone is now extensively used as a substitute 



432 CEMEXTS AND CONCEETES 

for natural stone^ for window heads, string courses, 
sills, columns, copings, keystones, and many other archi- 
tectural, constructive, and decorative features. Fig- 
ures, animals, bas-reliefs, capitals, panels, can be made 
in fine concrete with all the relief, undercut, and fine 
detail which distinguishes high-class from inferior 
work. Cast work has the advantage over in situ work 
that Ruy defect can be detected previous to fixing. The 
methods of moulding and casting various works are 
given in the following pages. 

Concrete Dressings. — Architectural works, especially 
large or plain parts, are generally cast in wood moulds. 
If there are ornamental parts in the blocks, a combina- 
tion of wood and plaster, and sometimes gelatine, is 
used for the moulds ; wood for the main or plain parts, 
plaster for circular or moulded parts, and gelatine for 
undercut parts. The plaster or gelatine, as the case 
may be, is screwed on or let into rebated parts of the 
wood. Ornamental parts are sometimes cast separately, 
and then fixed on the main cast. They may also be 
cast separately and laid into the main mould (face 
inwards), and the whole is cast together in a somewhat 
similar way to that described for "bedded enrich- 
ments" in fibrous plaster cornices. 

Considerable skill and ingenuity has been displayed 
in the construction of wood moulds for casting concrete 
blocks for architectural purposes. Many methods have 
been emplo^^ed for fixing the sides and ends together, 
and also to the bottom of the mould, leaving one or 
more parts unfixed to facilitate the release of the cast. 
The primitive method is to fix the various parts of the 
mould with screws. This is a slow and unreliable 
process, as the continual screwing and unscrewing for 



HOW TO USE THEM 



433 



each cast soon wears the screw-holes, and the sides be- 
come loose and out of square, causing the casts to get 
out of their true form. Hinges, also hooks and eyes, 
have been used for the same purpose, but they are 
liable to the same defects as the screws when subject 
to long use. 




—Wedge Mould for Casting Blocks, Moulded 
Lintels, &c. 

NO. 27. 

Thumbscrews to fit into iron sockets are also used, 
but they are too expensive for ordinary work, and are 
unsuitable for small moulds. One of the most simple 
and reliable methods is the 'Svedge mould," invented 
by an architect. It is easily made, and expeditious in 
working. Even after long and constant use, the casts 
are alwaj^s accurate in form and size. The wedges and 
the rebated ends allow the various parts to be correct- 
ly fixed and held in position. Illustration No. 27 shows 
the method of construction. The various parts are 



434 



CEMENTS AND CONCRETES 



named, and the sketch is self-explanatory. When the 
moulds are extra deep, it is necessary to make two or 
more sets of tenons and wedges at each angle. When 
there are a large number of casts required the mould 
ends are strengthened by binding the projecting ends 
wdth hoop iron. This method has been adopted for 
casting a lot of blocks. Illustration No. 28 shows two 
useful kinds of moulds. Fig. 1 is a simple form of 
mould adapted for plain blocks, caps, lintels, &c. A, A, 
are the sides, which are grooved into the ends B, B, and 



Fig. I. 




NO. 28. 



held together by the bolts and nuts, C, C, two on each 
side. The bolts may be about % inch diameter, with 
a good-sized square-head at one end, and a washer and 
nut at the other. This^ having no bottom, is termed a 
bolted frame mould. It should be laid on a bench or 
moulding board before the cast is filled in. Fig. 2 is 
a section of a combined wood and plaster mould on the 
Avedge principle, adapted for casting a strong course 
moulding. A is a moulding board, l^/o inches thick, 
formed with two or more boards; a is one of two or 
more cross ledges, 1 inch thick, on which A, the ground, 
is nailed. B is a width board, 1 inch thick, which is 



HOW TO USE THEM 435 

nailed on to A. This gives a point of resistance to the 
plaster piece C and the side board G. D is a side board 
on which E is screwed. E forms the sloping part of 
the weathering. P is one of two or more vertical 
wedges which hold D E in position. The sockets for 
the wedges P are made between the cross ledges, so 
that the wedge will project below the ground A. This 
allows the wedges to be more easily driven out when 
the east is set. G is the back or plain side board. H 
is a fillet, 11/2 inches square, screwed on to the ground 
A. I and J are two folding wedges, or, in other words, 
wedges driven in opposite directions. These hold G 
in position. Two or ^ore of these folding wedges are 
required, according to the length of the mould. The 
same remarks apply to the vertical wedges F. The lat- 
ter form of wedge is only given as an alternative. The 
end pieces are held in position by dropping them into 
grooves in a similar way as shown in the previous fig- 
ure, with the exception that the grooves are cut in the 
sides instead of the ends. K is a gauge rule which is 
used for ruling the upper surface of the cast fair. This 
may also be done by working a straight-edge longi- 
tudinally. The dotted line at L, the concrete, indicates 
the wall line. The level part of the weathering up to 
this line, or if splayed from the outer member of this 
line, must be finished smooth to allow the water to run 
freely off. When the cast is set, the wedges are with- 
drawn, and the sides and ends released. The east is 
then turned over on its back end or top side on a board, 
and then the plaster piece and the wood ground is taken 
off. If the cast is green, it should be turned over on 
old sacks or wet sawdust, so as to protect the arrises, 
and avoid fractures. 



436 



CEMENTS AND CONCRETES 



Illustration No. 29 shows a method commonly 
adopted for constructing moulds for sills and copings. 
Fig. 1 is the section of a mould for a window sill. A 
is the moulding board, made with two or more pieces, 
each 1% inches thick; a is one of two or more cross 
ledges, made with 1 inch stuff, on which A is nailed. B 
is the width board, made of % inch stuff, nailed on to 
A. C is a block, 1^ inches thick, which is nailed on 
to B. These blocks are placed about a foot apart, or 
so that they will carry the lining D, 1 inch thick. A 



Fig: t. 




Fig. 2. 



^^^rSiSl 







Fig. I. — Section of Mouli; for Casting Sills. 
Fig. 2.— Section of Mould for Casting Coping. 

NO. 29. 



groove or an iron tongue E is made in B, and a piece 
of thick hoop iron or iron bar is placed loosely in the 
groove before the cast is filled in. F is a fixed side, 
1% inches thick. G is a fillet,. 1% inches square, nailed 
on to F, and screwed on to moulding board A. H is a 
loose side, 1^4 inches thick, on which the fillet I is 
nailed. J is one of two or more clips, which turn on 
a screw, and. are used to hold the loose side H in posi- 
tion. These clips are made and used in the same way 
as described for fibrous slabs. As compared with 
wedges, clips are always in position ready for use, are 



HOW TO USE THEM 437 

not liable to be mislaid, and when the fillets are fixed 
on to the side pieces, the clips keep the sides from 
rising as well as expanding. K is a throating or water 
groove, which is formed in the concrete L, with a rule 
having a rounded edge. Two blocks, dished at the 
inner ends, must be fixed one at each end of the mould, 
so as to form a stool or bed for the superstructure. The 
position and form of the groove is obtained from sink- 
ings cut in the end pieces of the mould. The end pieces 
are held in position by grooves cut in the side pieces 
in a similar way, as already described, with the excep- 
tion that the grooves are cut in the side pieces, instead 
of the end pieces. When setting out the mould, an 
extra length must be allowed for the side pieces for the 
grooves. A part of the upper surface of the cast (be- 
ing the part which projects beyond the line of wall) 
must be finished fair by hand at the same time as form- 
ing the water groove. This must be done while the cast 
is green. When the cast is released from the mould, 
the iron tongue will be found firmly embedded in the 
concrete. Fig. 2 is a section of a wood mould adapted 
for casting wall copings. A is the ground of a mould- 
ing board, which may be made of li/i-inch stuff, and in 
2 or more widths ; a is one of two or more cross ledges, 
1 inch thick, on which A is fixed. B, B, are blocks 
about liy4 inches thick, placed about 1 foot apart. C, 
C, are linings, 1 inch thick, nailed to B, B. D is a 
fixed side, I14 inches thick. E is a fillet, 1% inches 
square, fi-xed to D, and then screwed on to A. F is a 
loose side, li/4 inches thick, on which is nailed the fillet 
G, 1% inches square. This strengthens the sides and 
affords the fixing point for the clip H. The water 
grooves I, I, and the hollowed part in the middle of the 



438 CEMENTS AND CONCRETES 

concrete J (made to save materials in weight) are 
worked from the end pieces of the mould, which are let 
into the grooves, as described in the previous diagram. 
If the moulds are deep, wood or iron clamps may be 
fixed across the sides to keep them in position, as shown 
by K. The moulding boards in this and the previous 
figures, if strongly made, can be used for a variety of 
similar purposes. A¥hen introducing cast instead of 
run moulded work, I used iron and zinc plates to 
strengthen and make more durable plain surfaces on 
wood moulds ; but owing to the expense and trouble in 
fixing the plates to the woodwork, they were aban- 
doned, and by using a better class of wood, and in- 
durating the surface of the mould with hot paraffin 
wax, sharp and clean casts Avere more cheaply pro- 
duced. Cast-iron moulds may be used where there is 
a large number of casts required. They may also be 
advantageously used for stock designs, such as plain 
moulded balusters. Wood moulds are rendered more 
durable and impervious to wet by brushing them with 
hot paraffin wax, and then forcing it into the wood by 
ironing with a hot iron. The use of paraffin wax and 
oil has already been described. 

Mouldings Cast ''In Situ." — Casting cornices, cop- 
ings, &c., in situ is now frequently employed for con- 
crete. The advantages of this system over shop cast 
work, are, that the work is readily done, and the cart- 
age or moving from the workshops to the building, and 
the fixing, are dispensed with. 

Illustration No. 30 shows the method of constructing 
and fixing various kinds of casting moulds for in situ 
work. 

Fig. 1 shows the section of a cornice, casting mould, 



HOW TO USE THEM 



439 




(A 

2; 



o 
o 
o 



u 
f- 
u 
(4 
u 
2 

o 

o 
r, 

< 

u 

O 

fa 

CO 

Q 
.-i 

O 



2 

f 

. a> 
< 

2 H 

O JX 

I ^ 

t-, .5 
.P a, 

V-. o 

o <2 
o o 

• ^ d 

• .£/^ 

<u c 

<-> "r! 

SO 

o 



3 CO 

O 



o 

o 
o 



o 



I 
4 



B 



b/) 

•S c 
-^ U 
S 

'O 

CJ 



» 

^ 



440 CEMENTS AND CONCEETES 

and supporting bracket. Wood moulds are generally 
used for small or plain mouldings, but where the profile 
is undercut or of an intricate nature, a plaster mould 
is preferable, as it is easier and cheaper to construct a 
plaster mould than cut the irons which are necessary 
for a wood mould for a special design. Fibrous plaster 
moulds may be used for this class of work, but to illus- 
trate another method a combined wood and plaster 
mould is given. M is a moulding board to strengthen 
the plaster profile, and on Avliich it is run. The board 
may be made in two or more pieces, each about 1 inch 
thick, and in width according to the depth of the mould- 
ing, and in length as required, the whole being held 
together by cleats H, which are nailed about 3 or 4 feet 
apart. Broad-headed nails are then driven in at ran- 
dom, leaving the heads projecting, to give a key for 
the plaster profile P. The profile is then run with a 
reverse running mould. It will be seen that this profile 
is undercut, therefore a loose piece L is required to 
enable the mould to draAV off the moulding. The re- 
verse mould and loose piece are constructed in the same 
way as described under the heading of "Reverse Mould- 
ings." It may be here remarked that it is sometimes 
useful to have an "eye" inserted in the loose piece to 
give a better hold for the fingers when taking the loose 
piece off the moulding. The eyes are made by twisting 
a piece of strong wire round the handle of a tool bruch, 
leaving one end in the form of a ring, and the other 
bent outwards so as to form a key. The eyes are fixed 
about 3 or 4 feet apart, the fixing being done by cut- 
ting a hole in the loose piece and bedding the shank of 
the eye with plaster, and then cutting a slot in the 
main part of the mould to receive the ring of the eye 



HOW TO USE THEM 441 

as shown at E. The mould is held in position by the 
bracket B, fixed 4 or 5 feet apart. The mould is further 
secured by the stay S, the other or inner end of the 
stay is fixed on to the main wall. It will be understood 
that a plaster mould for this purpose should be dry and 
hard, and then well seasoned with linseed oil, or with 
a hot solution of paraffin wax. After the mould is fixed 
in position it is oiled, and then the concrete C is filled 
in, taking care that the surface of the mould is first 
covered with a thin coat of neat cement. The mould 
may be oiled with paraffin oil; but if the mould is in- 
clined to "stick/' oil it with '^ chalk oil," i. e., paraffin 
oil and French chalk, about the consistency of cream. 

When the concrete is set, the brackets are removed, 
and the mould taken off. The mould in this case would 
draw in the line of the arrow A. The loose piece is 
then taken off. It is here that the use of the eyes will 
be found. Before removing the brackets it is advisable 
to prop the mould, in case it may drop off and break 
the fragile portions of the mould or parts of the cornice. 
A heavy mould hanging in this position, especially if 
the profile is flat, or in good working order, is apt to 
drop, hence the necessity of props. If the mould clings, 
or, as more generally called, "sticks fast," gentle tap- 
ping with a heavy hammer will ease or spring it, and 
allow it to be taken off. A heavy hammer is more ef- 
fective in making the mould spring than a light ham- 
mer, as the force required for a light hammer is apt to 
injure the mould. This is why a heavy hammer with a 
flat head is best for plaster piece moulding. 

Fig. 2 is the section of a string moulding with the 
casting mould and bracket. A chase is formed in the 
brickwork to allow it to bond, and the joints and the 



442 CEMENTS AND CONCRETES 

surface of the brickwork are cut out and hacked to give 
a further key to the moulding. M is the mould (in this 
case made of wood). The profile is drawn without any 
undercut parts, so as to allow the mould to draw off in 
one piece. B is the bracket^ and C is the concrete. The 
same directions for casting Fig. 1 appty to this and 
the other moulding here shown. A drip member, as 
shown at the top member of both cornices, is generally 
used for exterior mouldings^ to prevent the water run- 
ning over the wall surface. 

Fig. 3 is the section of a wall coping and the casting 
mould. M is the mould, a similar one being used for 
the other side. A mould for this purpose is best formed 
with flooring boards about 1 inch thick, and fixing them 
together as shown. The drip D is readily formed by 
sawing an inch bead through the centre, and nailing it 
on the bottom. Two forms of brackets, B and B, are 
here given. One is cut out of the solid, and the other 
made of two pieces of wood nailed together. 

Fig. 4 is the section of a casting mould for a saddle- 
back coping. R is a quarter-round piece of wood fixed 
in the angle of the mould to form a cavetto, which is 
sometimes used in copings. D is an angular-shaped 
drip, sometimes used in place of a circular one. T is 
part of a template used for forming the saddle-back of 
the coping. 

Fig. 5 is the section of a mould for a coping with 
splaj^ed or chamfered angles. S is a triangular strip 
of wood fixed in the angle and the top of the mould to 
form the splays, and D is a circular drip. 

Concrete mouldings that are deeply undercut or in- 
tricate in profile may be cast in situ by the use of the 
''Waste Mould Process." 



HOW TO USE THEM 443 

Modelling in Fine Concrete. — Figures of the human 
and animal form, also emblems, trade signs, and build- 
ings, are now being made in fine concrete. The work 
may be executed in situ, or in the moulding shop, and 
then fixed in position. For important works a plaster 
model is first made, and placed in position, so as to 
judge of the effect before committing it to the perma- 
nent material. For this purpose the model is first 
modelled in clay, and then it is waste-moulded, and a 
plaster cast obtained. After the model is approved it 
is moulded, and then cast in the fine concrete. The 
material is composed of Portland cement, and a light, 
but strong, aggregate ; and the cast is made in a similar 
way to that described for casting vases. The material 
may be colored as required to suit the subject. The 
general method of executing figures ''on the round" 
in fine concrete or Portland cement is to model the 
figure direct in the cement on an iron frame, and then 
to fix it in its permanent position. This is effected by 
first making a full-sized sketch of the proposed figure, 
then setting out on this the form of the necessary iron- 
work to serve as frame or skeleton to form an internal 
support. This iron frame also forms a core to enable 
the figure to be made hollow, and serves as a permanent 
support for thin parts and extremities of the figure. 
The quantity, size, and form of the iron frame is regu- 
lated by the size, form, and position of the figure. For 
instance, if the model of a full-size lion is required, first 
make a rectangular frame to suit the feet of the lion 
and the base on which the figure stands. The base 
frame is made of iron bars, 1% inches wide by i/4 iiich 
thick, fixed on edge. Then set out four leg-irons, and 
connect them on the base frame, and then set out one 



444 CEMENTS AND CONCRETES 

or two body-irons, and connect them with the leg-irons. 
After this set ont a looped piece to fit the contour of 
the neck and head, and fix it to the body-iron. Now 
set out the tail-iron. This is best formed with an iron 
pipe, and it should be made to screw on to the body- 
iron. This allows the tail to be unscrewed when the 
model is finished, and screwed on affcer the model is 
fixed in position, thus enabling the model to be more 
freely handled, and with less risk of breakage when 
moving and fixing in its permanent position. 

Having made the frame, place it on a stout modelling 
board, keeping the base frame from 1 to 3 inches above 
the board, according to the depth of the base ; the frame 
being temporarily supported with four pieces of brick 
or stone. This is done to allow the base frame to be 
enveloped with concrete. This done, fix wood rules, cut 
to the depth of the base, on the board, so as to form 
a fence on all sides of the base. Then fill in the base 
with concrete ; and when this is set, proceed with the 
coring out, so as to obtain a hollow model. 

In order to decrease the weight of concrete figures 
''on the round," and to enable them to be more easily 
handled and hoisted when fixing them in their perma- 
nent positions, they should be made hollow. This is 
effected by making a round skeleton frame with hoop- 
iron, or with wire-netting, for the body, neck, and head, 
and other thick parts. This metal skeleton must be 
built on and securely fixed to the main iron frame. The 
whole, or parts of the figure, may also be cored out with 
shavings or tow, and held in position with tar bands or 
canvas strips, dipped in plaster. Tow is an excellent 
material for forming cores. By making up the inner 
parts with dry tow, and then dipping tow in plaster for 



HOW TO USE THEM 445 

the outside coat, the core can be made to any desired 
shape, and also leave the necessary thickness for the 
concrete. To prevent the material slipping down by 
its own weight, pieces of iron or wood, in the form of 
crosses, are fastened with copper wire or tar rope to 
the iron rods, which are used as single supports. These 
iron or wood jjieces must be fixed in all directions, and 
in such a way that the material is held up by them. 
For small extremities, such as fingers of human figures, 
beaks of birds, fins of fishes, horns and tails of animals, 
iron rods should be fixed on the main frame, and the 
parts to be covered with cement must be notched or 
bound at intervals with copper wire or tar rope. The 
distance between the core and the finished face of the 
figure is of course the actual thickness of the model. 
This thickness may vary from 1 inch to 3 inches, or 
even 4 inches at some parts. An actual thickness of 2 
inches will be sufficient to give the requisite strength. 

When the core is made, cover it with a coat of Port- 
land cement and old lime putty, in the proportion of 3 
of the former to 1 of the latter, and add sufficient tow 
or hair to give tenacity. If there are open spaces in 
the skeleton iron work, bridge them over with bits of 
tiles and cement. The whole surface, after being coated, 
must be well scratched with a nail, to give a key for 
the roughing out coat. This scratched coat must be 
allowed to set before proceeding with the actual model- 
ling. The stuff for roughing out is composed of 2 
parts of Portland cement and 1 part of fine aggregate. 
Crushed bricks, stone, or pottery ware passed through 
a sieve having a % inch mesh may be used as aggre- 
gates. The finishing stuff is composed of fine sifted 
Portland cement. The addition of a fifth part of old 



446 CEMENTS AMD COXCRETES 

lime putty to tlie cement makes tlie stuff more mellow, 
and works freer and sweeter. Tlie modelling is done as 
described for in situ work. Tlie finishing coat can be 
colored to anv desired tint, as alreadv described. 

t. r C 

Concrete Fou/itainsj: — Fine concrete is an excellent 
material for tlie construction of fountains. It is ob- 
vious that a vast amount of cutting and consec[uent 
waste of material is iiiTolved in the executing of foun- 
tains, ""on the round.'" when natural stone is employed. 
Saving of material, and a corresponding reduction in 
the cost, is efi'ected bv use of a material that can be 
easily cast, and is at the same time durable and im- 
pervious. These equalities combined are found in arti- 
ficial stone composed of fine concrete. Being readily 
made in large blocks {smy sized basin can be made in 
one piece'', there is no jointing required, as is the case 
with terra cotta. which is another form of artificial 
stone. Fountains composed of fine concrete are made 
in a similar way to that described for making and cast- 
ing vases. 

Concrete Tanks. — Concrete tanks to contain water, 
and for a variety of manufacturing purposes, are now 
lars:elv in use. Thev are stroiio- and durable, and hav- 
ins: hard smooth surfaces, thev are easilv washed and 
kept clean. Being impervious to vermin, damp, and 
atmospheric infiuences, they are the coolest and most 
sanitarv water cisterns that can be used. Cattle trousks 
are best made in concrete. Concrete tanks have been 
used as water and silicate baths for indurating con- 
crete casts, and during their constant use for over a 
decade no signs of cracks or damp are visible. They 
were made in one piece, varying in size from 6 feet up 
to 18 f^et lonor. 3 feet to 7 feet wide. 2 feet 6 inches to 



HOW TO USE THEM 447 

4 feet high, and from 3 to 4% inches thick. Some were 
cast, but the large ones were made in situ. The method 
of construction (for in situ work) being simple and ex- 
peditious, the total cost is small. For a tank 9 feet long, 
4 feet 6 inches wide, 2 feet 6 inches high, and 3I/2 inches 
thick, first frame up wood sides and ends to the above 
length, width, and height, then make inside boards, 
the lengths and widths being the same as above, less 
the tank thickness, and the heights less the bottom 
thickness. The sides and ends are hung by means of 
cross battens laid on the upper edges of the outside 
framing, and kept in position with inside stays. This 
leaves an open and continuous space at the sides, ends, 
a'nd bottom. The constructive materials are 1 part of 
Portland cement and 2 of fine slag or granite, gauged 
stiff, and laid over the bottom. Next, the open sides 
and ends are filled up, taking great care that the whole 
mass is thoroughly consolidated by ramming. The 
stuff for the sides and ends should be laid in layers 
from 6 to 8 inches deep, each layer being well rammed 
before the next is laid. 

The angles are strengthened by inserting angle irons 
during the process of filling in. As soon as the concrete 
is set the inner boards are removed, and if the surface 
is smooth or dry, it must be keyed with a coarse drag 
or a sharp hand pick. It is then swept and wetted to 
cleanse it and stop the suction, so as to ensure perfect 
cohesion, and allow the final coat to retain its moisture 
during the process of trowelling and the stuff setting. 

The finishing coat is composed of neat cement, the 
finer ground the better, as percolation through con- 
crete made with a finely ground cement is less liable 
than when made with a coarsely ground cement. 



448 CEMENTS AND CONCRETES 

The final coat is laid about 3/16 inch thick, and pre- 
ceded by brushing the surface with liquid cement to 
fill up all crevices, and afford better adhesion between 
the surface and the final coat. When the stuff is firm, 
it is well trowelled to a fine and close surface. The 
outer boards are then removed, and the surface finished 
in a similar way. 

Concrete Sinks. — Concrete sinks can be made to any 
desired size or form. They are cast in wood or plaster 
moulds, and are composed of 1 part of Portland cement 
to 2 parts of fine crushed granite or other hard aggre- 
gate. They are made with rebated holes for traps. The 
ordinary size are as follows : 2 feet 6 inches by 1 foot 
8 inches ; 2 feet 9 inches by 1 foot 8 inches ; and 3 feet 
by 2 feet, all 6 inches deep, and from 2 to 3 inches thick. 

Garden Edging. — Plain and ornamented edgings are 
now made in concrete. They are made in various 
lengths. The most useful size is 3 feet long, 6 inches 
deep, and 2 inches thick. They can be made to any 
curve, and tinted to any shade. 

Concrete Vases. — During the last half-century thou- 
sands of vases, composed of fine concrete — commonly 
called "artificial stone" — have been used for the dec- 
oration of buildings and practical use in gardens, con- 
servatories, &c. For vases that are cast in sections the 
thickness of large and open parts, such as the "body," 
are regulated by means of a plaster core, which is 
placed in the open mould. The contour of the core 
must be so arranged that the cast will draw from the 
core, or vice versa. For some forms of vases, the core 
must be made in pieces similar to a piece mould. The 
method of making, moulding, and casting — the latter 
by the aid of a template instead of a core 



HOW TO USE THEM 449 

Concrete Mantel Pieces. — Cliimney-pieces of all sizes 
and shapes are now extensively made in fine concrete. 
They are generally made in wood moulds, plaster 
moulds being let in the main mould for ornamental 
parts. They are often made in colored concrete. 

Colored Concrete. — Concrete casts, also work laid in 
situ, can be colored to imitate any natural stone. This 
is effected by mixing mineral oxides of the required 
color with the cement used for the surface coat. The 
color coat should not exceed % inch in thickness, as 
oxides are too expensive to use for the entire thickness 
of the cast. The quantity of oxide to be added to the 
cement depends upon the strength of the oxide. Some 
are much stronger than others. Five per cent, of a 
strong oxide will impart a close resemblance of the 
desired color to the concrete, but a weak oxide will re- 
quire from 10 to 15 per cent., and even 20 per cent., to 
obtain the same color. Some of the red oxides range 
in color from scarlet or Turkey red, gradually deepen- 
ing to chocolate. Some oxides contain 95 per cent, of 
pure ferric oxide, which is made from copperas, .or, 
scientifically speaking, sulphate of iron. This is a by- 
product, and is frequently evolved from waste acid 
liquors at tinplate works, and is obtained in large quan- 
tities from South Wales. This kind of oxide is far 
more suitable for coloring concrete than ochres and 
most of the earthy oxides. Earthy colors, like Venetian 
red and umber, soon fade and have a sickly appearance. 
The oxides should be intimately mixed with the cement 
in a dry state before it is gauged. The mixing is gen- 
erally done by hand, but better results are obtained by 
the use of grinding machine. It is a safe plan to try 
various proportions of color and cement and gauge 



450 CEMENTS AND CONCRETES 

small parts, and when set and dry select those most 
suitable for the desired purpose. All cast work, as soon 
as extracted from the moulds, should be examined, and 
any blubs stopped and chipped parts or other minor 
defects made good while the work is moist or green, 
using neat cement and colors in the same proportion 
as used for the surface stuff. Colored surfaces may be 
greatly improved by brushing the cast as soon as set 
with a solution of the same color as used for the sur- 
face coat. A color solution, made by mixing the color 
with water and a solution of alum, is very useful for 
coloring Portland cement, with or without sand. If this 
coloring solution is brushed over the surface while it 
is moist or semi-dry, a good standing color can be ob- 
tained without mixing color wdth dry cement. This 
method will be found useful for sgraffitto, &c. 

A novel and color-saving method, for coloring the 
upper surfaces of slabs or other flat casts, is effected 
by first filling in the mould in the usual way, then 
placing the colored cement in a dry state in a hand 
sieve, and then violently shaking or tapping the sides 
of the sieve, so as to sprinkle the colored cement uni- 
formly over the surface until it is nearly 1/16 inch 
thick. The surface is then trowelled in the usual way. 
The sprinkling must be done as soon as the main body 
of the stuff is ruled off^ so as to obtain a homogeneous 
body. Another and a novel method which may be ad- 
vantageously employed for finishing slab or other large 
surfaces in a mould is as follows : A fine finished face 
is more readily obtained by using a smoothing knife 
(for brevity termed a ''shaver") than by a trowel. A 
shaver is a piece of polished steel about 3 inches wide 
and % inch thick, the length being regulated according 



HOW TO USE THEM 451 

to the width of the mould, and allowing about 8 inches 
at each end for handles. For instance, for a slab 2 feet 
wide, the shaver should be 3 feet long. This allows 2 
feet for the surface of the cast, 3 inches to bear on the 
rims of the mould, each l^/^ inches wide ; 8 inches for 
the handles, each 4 inches long; and 1 inch for play. 
One edge or side is cut to an angle of 45°, so as to 
form a cutting edge. The method of filling in, coloring, 
and finishing the surface of the slab is as follows : First 
fill in the mould with the concrete, ramming and beat- 
ing it as already described until the stuff is about 1/16 
inch above the mould rims, then clean off the stuff on 
the rims with a wood template (rebated to fit the width 
of the rims), and lay the shaver flat on the rims, keep- 
ing the cutting edge outwards, and then push it for- 
ward, keeping it flat on the rims, so as to shave off the 
superfluous stuff. This done, sprinkle the colored ce- 
ment, with the aid of a sieve, until about 1/16 inch 
thick; then clean the rims again, and pass the shaver 
forwards and backwards twice or thrice, which will 
leave a straight, smooth, and uniform-colored surface. 
This method effects a considerable saving in the amount 
of oxide and of time. The thickness of the coloring 
stratum is reduced mechanically to the minimum (about 
1/32 inch), which is all sufficient for coloring purposes 
where the surface is not subjected to frictional wear. 

As already mentioned, bullocks' blood mixed with 
cement gives a near resemblance to red brick, but it is 
not a desirable material to work with, and the same 
effect can be obtained by the use of red oxides. Red 
sand, brick, and stone, all finely ground, have been em- 
ployed for coloring cement surfaces^ but if too fine or 
in large quantities they weaken the surface; and if 



452 CEMENTS AND CONCRETES 

coarse-grained they possess little coloring effect, be- 
cause the particles are liable to show singly^ causing a 
spotty appearance, or the cement entirely covers the 
surface of each particle of sand. Powdered glass, mar- 
ble, flint, alabaster, metal filings, and mineral coloring 
can be effectively employed for coloring concrete sur- 
faces by mixing with the cement used for the surface 
coat. The surface is improved by rubbing and stoning, 
also polishing, after the Avork is drj^ Other methods 
and quantities of colors for coloring Portland cement 
surfaces are given. 

Fixing Bloclcs. — Concrete fixing blocks do not shrink, 
warp, or rot. Consequently they are superior to wood 
filletSy &c. They are principally used in concrete floors, 
stair landings, and walls, as bearings and flxing points 
for wire-lathing and fibrous plaster work. Floor boards 
may also be fixed to them. They are also built into 
brick walls for similar purposes, as well as for external 
wall tilings. For ceilings, stair soffits, and landings, 
the blocks are laid on the centrings where required, 
and permanently secured by laying concrete between 
and over them. For bearings and fixing flooring boards, 
they are secured flush. 

TYPICAL SYSTEMS OF REINFORCED CONCRETE 
CONSTRUCTIONS FRO:\r VARIOUS SOURCES. 

Of the interesting features of modern civil engineer- 
ing, interesting because of their extreme novelty and 
successful application, reinforced concrete is probably 
most noteworthy because of its unique adaptability. 
How striking is the influence of steel reinforcement is 
best exemplified by a reference to Fig. 1, There twQ 



HOW TO USE THEM 453 

beams are shown designed to carry ordinary floor loads, 
the one made entirely of concrete and the other of con- 
crete with a sheet of expanded metal imbedded in the 
tensile portion of the beam. The saving in mere weight 
of concrete alone is apparent; and when we remember 
that the adoption of floor beams entirely of concrete 
means an increase of thickness of nine inches or as- 
suming five to eight floors, an increase in the total 
height of the building (with extra cost and heavier 
walls, together with heavier foundations to carry them) 
of from four to six feet, we see that even as regards 
initial outlav for materials, the introduction of settle 
reinforcement into concrete construction is of import- 
ance. 

So far as economy in initial cost of materials is con- 
cerned, reinforced concrete is undoubtedly cheaper 
than either concrete or steel alone. It is not very easy 
to demonstrate this economy except by comparative 
cost in individual cases, but an approach to a systematic 
comparison has been made by Mr. Walter Loring Webb, 
as follows : A cubic foot of steel weighs 490 pounds. 
Assume as an average price that it can be bought and 
placed for 4.5 cents per pound. The steel will therefore 
cost $22.05 per cubic foot. On the basis that concrete 
may be placed for $6 per cubic yard, the concrete will 
cost 22 cents per cubic foot which is 1 per cent of the 
cost of the steel. Therefore, on this basis if it is neces- 
sary to use as reinforcement an amount of steel whose 
volume is in excess of 1 per cent of the additional con- 
crete which would do the same work^ there is no econ- 
omy in the reinforcement, even though the reinforce- 
ment is justified on account of the other considerations. 
Assuming 500 pounds per square inch as the working 



454 



CEMENTS AND CONCRETES 



compressive strength of concrete, and 16,000 as the per- 
missible stress in steel, it requires 3.125 per cent of steel 
to furnish the same compressive stress as concrete. On 
the above basis of cost, the compression is evidently 
obtained much more cheaply in concrete than in steel 
— in fact, at less than one-third of the cost. On the 
other hand, even if we allow 50 pounds per square inch 
tension in the concrete and 16,000 pounds in the steel, 
it requires only 0.21 per cent of steel to furnish the 




Fig. l.-;^These Beams Are Designed to Carry the Same 

Load. The Upper is of Reinforced Concrete, tlie 

Lower of Plain Concrete. 

same strength as the concrete, which shows that, no 
matter what may be the variation in the comparative 
price, of concrete and steel, steel always furnishes ten- 
sion at a far cheaper price than concrete, on the above 
basis at less than one-third of the cost. The practical 
meaning of this is, on the one hand, that a beam com- 
posed wholly of concrete is usually inadvisable, since its 
low tensile strength makes it uneconomical, if not actu- 
ally impracticable, for it may be readily shown that, 
beyond a comparatively short span, a concrete beam 
will not support its own weight. On the other hand, 



HOW TO USE THEM 



455 



on account of the cheaper compressive stress furnishect 
by concrete, an all-steel beam is not so economical as 




Eiff. 2.— Types of Steel Reinforcin<? Rods. 

a beam in which the concrete furnishes the compres- 
sive stress and the steel furnishes the tensile stress. 




Fig. 3.— A Reinforced Concrete Pier for Railway 

Traffic. 

This statement has been very frequently verified when 
comparing the cost of the construction of floors de- 



456 



CEMENTS AND CONCRETES 



signed by using steel I-beams supporting a fire-proof 
concrete floor, and that of a concrete floor having a 
similar floor slab but making the beams as T-beams of 
Reinforced concrete. 

A good idea of reinforced concrete construction can 
be obtained from Fig. 3, which is an isometrical pro- 
jection of a portion of a pier strong enough to carry 
the heaviest railway traffic. The disposition of the 
steel work is shown in the piles, the main girders, and 
beams ; and the manner in which the steel rods run- 
ning along the tensile or bottom side of the girders 
and beams are bent up over the top of the pile, which 
is here the tensile member (the beams being continu- 
ous), and then down again to the bottom of the girders 
and beams, is most instructive. 




- -r;wyaa^-,gr'??5^^yi 




Fig". 4.— Method of Joining Columns and Floors. 

The sections of the steel employed vary in different 
systems, being round, flat, square, angle, and tee — Fig. 
2. In all cases the simplest section is the best, as it 
costs less, and readily allows the concrete to be rammed 
into the closest contact with the entire surface of the 
armoring. In America the Ransome system is most 
extensively used — a system in which a bar of twisted 



HOW TO USE THEM 



457 



steel is employed. Small sections are better than large 
ones, for by their use we obtain a more uniform dis- 
tribution of stress in the steel; we can also readily 
bend and work them into any required shape ; and 
finally the most economical disposition of material is 
obtained, the metal being placed at the maximum dis- 
tance from the neutral axis. 




^^^^' u^ ?A '"'V '' \ '''>■ ,'' 





m ,vi 'J/ V '"'i ^,^^ 



Fig. 5.— The Monier System. 

Expanded metal meshing (Fig. 6) is increasingly em- 
ployed, more particularly in the lighter forms of con- 
struction. It consists of sheets of metal which have 
been mechanically slit and expanded, so as to produce 
a network. This type of reinforcement has many and 
obvious advantages. Its mere existence is proof of good 
steel, and it forms an excellent key for concrete too 
thin to permit reinforcement in the form of rods ; thus 
it is very useful for concrete plaster, ceiling, and parti- 
tion wall work. A good example of reinforced con- 
crete in which expanded metal is used may be found 
in the Monier system (Fig. 5). An improvement on 



458 CEMENTS AND CONCRETES 

this system is the Clinton method (Fig. 11) of using 
an electrically welded wire netting in combination with 
concrete. Clinton fabric consists of drawn wire of 6 
to 10 gauge, which' may be made in lengths up to 300 
feet. The system is therefore a continuous bond system, 
which prevents the entire collapse of a span unless the 
weight imposed is sufficient to break all the wires. 




Fig* 67— Expanded Metal. 

Columns and Piles. — Reinforced columns are made 
with either square, rectangular, or circular sections. 
They are reinforced with from four to twenty rods, the 
diameters of which vary from % to 2% inches. The 
rods are placed as nearly as practicable to the circum- 
ference of the column, so as to give the greatest radius 
of gyration for the section; but they are never placed 
so near the surface that they have not at least one or 
two inches protective covering. The steel so disposed 
is able to take up the tensile stresses which may be 



HOW TO USE THEM 



459 



induced in the column by eccentric loading, lateral 
shocks wind pressure, and the pull of belting. 

Columns and piles are made in wooden boxes, each 
consisting of three permanent sides and a fourth side 
which is temporary and removable. Under the patent 
rights of Francois Hennebique the reinforcing is placed 




fig. 7. -Baxtsomc &»yslem ot Erecting Columns. 



in these boxes, and adjusted by gauges to within one or 
two inches of the sides. The concrete is laid and 
rammed, about six inches at a time, with small hand 
rammers. The open side of the box is built up by 
battens fitting into grooves in the permanent sides, as 
the work proceeds ; this enables inspection of the work 



460 



CEMENTS AND CONCRETES 



to be made, and facilitates the placing of the ties at the 
proper positions. The ties are made of round wire 3/16 







Fig. 8.— Wood Centering and Ransome Steel Bars for 50-t'oot 

Floor Span. 



inch diameter and are dropped down over the top of 
the steel rods. They are spaced down two-inch centres 



HOW TO USE THEM 



461 



at the bottom and top, to twelve-inch centres in the 
centre of length of the column, and are intended to 
prevent the steel rods from spreading out under the 
action of longitudinal loads. Fig. 4 shows the method 
of joining columns to the floor. 




Fig. 9.— Concrete Power Plant in Course of 
Construction. 



In the Ransome columns as exemplified in a recently 
constructed factory building (Fig. 7), the vertical re- 
inforcement consists of round rods with the connections 
made about 12 inches above the floor line; in order that 



462 



CEMENTS AND CONCRETES 



these rods might be continuous the ends were threaded 
and connected with sleeve nuts, thereby developing the 
full strength of the rods. Horizontal reinforcement 
was also used, consisting of hoops formed by a spiral 




Fig. lO.—Slalbs of Concrete Ready for Roof. 



made from ^4 iiich diameter soft wire, having a pitch 
or spacing of 4 inches in the basement columns, and 
gradually increasing to a pitch of 6 inches in the top 
story (Pig. 12). 

According to Mr. Henry Longcope the first innova- 
tion in concrete piles was the sand pile, produced by 



HOW TO USE THEM 



463 



driving a wooden form in the 
ground and withdrawing it, 
the hole being filled with 
moist sand well rammed. The 
next method adopted was to 
drive a metal form into the 
ground and after withdrawal 
to fill the hole with concrete. 
This was not successful, as it 
was open to the serious objec- 
tion that on withdrawing the 
form, the ground would col- 
lapse before the concrete could 
be inserted. Still another 
method was introduced, which 
consisted in dropping a cone- 
shaped five ton weight a num- 
ber of times from a consider- 
able height, in order to form 
a hole, which was afterward 
filled with concrete. This 
method never passed the ex- 
perimental stage. Coming to 
more successful systems we 
may mention a method of 
moulding a pile of concrete, 
allowing it to stand, and then 
driving it into the ground, a 
cap being used to protect the 
head. 

Of modern systems which 
have proven successful, Gil- 
breth's pile must first be re- 



rs 






C 

B 

e 
© 






464 



CEMENTS AND CONXRETES 




HOW TO USE THEM 465 

corded. Gilbreth used a molded corrugated taper pile, 
cast with core hole the entire length of the pile, which is 
jetted down by a water jet and finally settled by hammer 

blows. 

Features which recommended the Gilbreth piles are 
the opportunities for complete inspection before driv- 
ing and the fact that they save time because they can 
be cased while excavation is going on. After being 
driven they can be loaded immediately. Naturally they 
present considerable skin friction. The making of these 
piles above the ground surface also does away with the 
possibility of their being damaged or squeezed out of 
shape by the jar occasioned by driving forms for ad- 
joining piles. 

Still another method is used by Raymond. Under 
this system piles are usually put in by either of two 
methods, the jetting method or the pile core method. 
The water jet system is used only where the material 
penetrated is sand, quicksand, or soft material that will 
dissolve and flow up inside the pile when the water is 
forced through the pipe, thus causing the shell to settle 
until it comes in contact with the next shell, and so on 
until the desired depth has been reached. The shells 
are filled with concrete simultaneously with the sinking 
process, and when necessary spreads are attached to 
keep the hole in perfect line with the pipe. The % 
inch pipe is left in the centre of the pile and gives it 
greatly increased lateral strength. If desired, the 
lateral strength may be further increased by inserting 
rods near the outer surface of the concrete. By this 
method, piles of any size up to two feet in diameter at 
the bottom and four feet at the top can be put through 



466 CEMENTS AND CONCRETES 

any depth of water and to a suitable penetration in 
sand or silt (water sediment). 

The pile-core method is the one most generally used 
for foundation work and consists of a collapsible steel 
pile core, conical in shape, which is incased in a thin, 
tight-fitting metal shell. The core and shell are driven 
into the ground by means of a pile driver. The core 
is so constructed that when the desired depth has been 
reached it is collapsed and loses contact with the shell, 
so that it is easily Avithdrawn, leaving the shell or cas- 
ing in the ground, to act as a mold or form for the 
concrete. When the form is withdrawn, the shell or 
casing is filled with carefully mixed Portland cement 
concrete, which is thoroughly tamped during the filling 
process. 

The simplex system uses another method in which 
the driving form consists of a strong steel tube, the 
lower end of which is fitted with powerful tooth jaws, 
which close together tightly, with a point capable of 
opening automatically to the full diameter of the tube 
while being withdrawn. The point of the form closely 
resembles the jaws of an alligator. At the same time 
the form is being withdra^vn, the concrete is deposited. 

It is so evident that concrete is vastly superior to 
wood in the construction of piles that it is almost su- 
perfluous to mention the points of superiority. Con- 
crete is not subject to rot or the ravages of the teredo 
worm, neither can the piles constructed of concrete be 
destroyed by fire, and no cost is attached for repairs. 
While it is not possible to give accurate statistics as to 
the life of a wooden pile, as it varies so much under 
different conditions, yet we know that in some cases 
a wooden pile is rendered worthless in a very few years, 



HOW TO USE THEM 467 

especially when the surrounding material is composed 
of rotted vegetation, or where the pile is exposed by 
the rise and fall of tides. It is also impossible to state 
the exact cost of a concrete pile, as it varies also ac- 
cording to conditions. Ordinarily speaking^ a concrete 
pile will cost from one and one-half times or two times 
as much as a wooden pile ; but in order to illustrate 
where a saving can be made, the following extract is 
given from a report on the piles driven at the United 
States Naval Academy at Annapolis, Md. : 

''The original plans called for 3,200 wooden piles 
cut off below low water with a capping of concrete. 
To get down to the low water level required sheet pil- 
ing, shorting and pumping, and the excavating of near- 
ly 5,000 cubic yards of earth. By substituting concrete 
piles, the work was reduced to driving 850 concrete 
piles, excavating 1,000 cubic yards of earth and placing 
of 1,000 cubic yards of concrete." 

In the work mentioned, the first estimate for wooden 
piles placed the cost at $9.50 each, while the estimate 
for concrete piles was placed at $20 each, yet the esti- 
mate based on the use of wood piles aggregated $52,840, 
while the estimate based on the use of concrete piles 
w^as $25,403, or a total saving in favor of concrete of 
over $27,000. 

In several instances piles have been uncovered to 
their full depth, and they were found to be perfectly 
sound in every particular. By surrounding the opera- 
tion with the safeguards provided, it is almost impos- 
sible to make a faulty pile. The concrete is made as 
wet as good practice will allow. Constant ramming and 
dropping the concrete from a considerable height tend 
to the assurance of a solid mass, then the target on 



468 CEMENTS AND CONCRETES 

the ramming line or the introduction of an electric light 
into the form shows what is being done at the bottom 
of the form. 

Floors, Slabs and Roofs. — The system of construction 
for floors, slabs, and roofs is determined by the extent 
of the work and the nature of the loads to be carried. 
If intended for small buildings and offices, the items 
can be made before erection (Figs. 9 and 10) ; but in 
the case of warehouses^ factories^ piers, and jetties, 
where live loads and vibrator stresses have to be borne, 
a monolithic structure is secured by building in molds 
directly on the site. For the lighter classes of mono- 
lithic structure, expanded metal is admirably suitable; 
it is also much used for the roofs of reservoirs, and for 
thin partitioned walls. The meshing is simply laid 
over the ribs or floor beams, which have been already 
erected, and the green concrete is applied to the acquired 
thickness, being supported from below b}^ suitable sup- 
porting work, which is remoA^ed as soon as the concrete 
has set. In cold storage factories, the floor beams and 
ceilings are invariably erected first, the floor being laid 
afterv^ard. The ceiling is then solid with the floor 
beams on their under side, and the floor is solid with 
them on their upper side, the air space between being a 
great aid to the maintenance of a low temperature for 
refrigeration. 

In the Monier floors the reinforcement consists of 
round rods varying from % inch to % inch diameter. 
The rods are spaced at about six times their diameter, 
and are crossed at right angles, being connected by 
iron Vvure bound round them. This artificial method of 
securing the rods takes considerable time, and is thus 
a somewhat costly process. To produce continuity of 



HOW TO USE THEM 469 

metal, the different lengths of rods are overlapped for 
about 8 to 16 inches^ and bound with wire. 

The Schluter are similar to the Monier floors, but 
the rods are crossed diagonally, and the longitudinal 
rods are of the same size as the transverse ones. The 
Cottancin floors have their rods interlaced like the 
canes of a chair seat or a basket, and the Hyatt floors 
have square rods with holes through which small trans- 
verse rods pass. Over fifty systems of reinforcing are 
in use, and in most cases the only points of difference 
are the shape of the section and the method of attach- 
ment and adjustment. 

Beams. — It is obvious that, as the span increases, a 
limit will soon be reached beyond which it is not eco- 
nomical to use plain_fioor slabs, for their dead weight 
becomes of such magnitude as to prohibit their use. We 
have thus to resort to a division of the main span by 
cross beams resting on columns, and the floor is laid 
on these beams, which are arranged to take as much of 
the load as to render it possible to reduce the thick- 
ness of the floor within reasonable limits. Reinforced 
concrete beams are typical of the construction in which 
the merits of two component materials are made to 
serve a common end ; but in the particular case of steel 
and concrete, the actual part played by the steel is 
not at all well understood. 

Speaking generally, beams do not differ in construe- 
tional details from floors. The same reinforcement is 
used in both, the only difference being, that as beams 
are usually deeper than floors, the shearing stresses be- 
come more pronounced, the greater provision has to be 
made for them by a liberal use of stirrups or vertical 
binding rods. In some systems the reinforcement con- 



470 CEMENTS AND CONCRETES 

sists entirely of straight rods, disposed in any part of 
the beam where tensile stresses are likely to be called 
into play. In others, specially bent rods are joined or 
welded to straight rods, disposed and when welding has 
to be done it would appear that wrought iron is more 
suitable than steel. 

It is usual to arrange the dimensions of the beams 
so that the whole of the compressive stresses are taken 
by that portion of the concrete on one side of the neu- 
tral axis; but in some cases, as with continuous beams 
or heavy beams of small depth, a portion of the rein- 
forcement is disturbed along compressed portion of the 
beam, the steel rods either taking up the excess of 
compressive stress over that at which the concrete can 
be safely worked, or else taking up the tensile stresses 
at the places where they occur over the supports. As 
a general rule we may take it that the economical depth 
for a reinforced concrete beam, freely supported at 
both ends, is one-twentieth the span, and is thus ap- 
proximately the same as that of a steel girder of equal 
strength. Reinforced concrete beams are now made for 
spans up to 100 feet for buildings, and 150 feet for 
bridges. But for each class of work beyond this limit, 
the weight becomes excessive. Several arched ribs, 
for much greater spans have^ however, been success- 
fully built. 

The beams are made in much the same way as piles 
and columns; they can be made in sheds on the site, 
or in the actual position they are to occupy when fin- 
ished. The ceiling and beams are erected first, the 
floor being afterward worked on the top of the beams. 
"We thus obtain a very perfect monolithic structure in 
which any vibration set up by machinery, falling loads, 



HOW TO USE THEM 471 

etc., will be of much less extent than with any ordinary 
type of building, in which there is often a great want 
of rigidity, the beams and arches being loose and able 
to vibrate independently of other parts of the struc- 
ture. 

Concrete being as weak in shear as in tension, pro- 
vision is also required to take the shearing stresses. 
Some American designers have to this end patented 
special forms of reinforcement bar, in which each main 
tension bar has projecting upward from it ties inclined 
at the angle of 45 deg. (Kahn system.) These ex- 
tend to the top of the bar and take the tensile stresses 
arising from the shear. The corresponding compres- 
sive stress at right angles to this is carried by the con- 
crete. The system is efficient and on large spans, where 
weight must be reduced to a minimum, it has its ad- 
vantages. 

Thus, in the Ransome system (Fig. 12), the shearing 
stresses at the end of a beam are taken up by inclined 
reinforcing rods imbedded in the concrete at the junc- 
tion of beam with column. 

Arches. — Concrete has long had an extensive ap- 
plication in the building of arches, but until the in- 
troduction of reinforced concrete the arches that could 
be economically and safely constructed were limited to 
spans of a few feet. The general rule that the line of 
resistance fell within the middl-e third had to be ob- 
served for simple concrete arches, as for those in brick- 
work and masonry; and the thickness of the arches 
at the crown was thus approximately the same whether 
built in either of these materials. The introduction of 
steel reinforcement, however, made it possible not only 
to reduce the thickness of the ring of a given load- 



472 



CEMENTS AND CONCRETES 






HOW TO USE THEM 

carrying capacity, but by suitably providing for tne 
tensile stresses to enable arches of much greater span 
and smaller rise to be built. Some general types of 
arches in reinforced concrete are shown in Figs. 13, 14, 
15 and 16. Fig. 13 shows an ordinary arch with top 
and bottom armature. In many cases where the ten- 
sile stresses can safely be carried by the concrete the 
top armature can be omitted. In the Melane arches, 
shown in Fig. 14, the top and bottom armatures are 
connected by ligatures, and in the Hennebique arches 
(Fig. 15) stirrups are used. As a general rule, hinges 
should be built at the stringings and the crown, for the 
calculations are much simplified, and the line of re- 
sistance goes through the hinges; the arches also ad- 
just themselves better to the load and to any slow 
temperature changes, and when the centering is struck 
the arch can better take its bearings without cracking. 
The methods of calculations for arches are as numer- 
ous as those for beams, and generally speaking are as 
irrational. The Monier system is the one most gen- 
erally adopted, and over 400 bridges built on this sys- 
tem now exist in Europe. In America expanded metal 
and Clinton electrically-welded fabric are often used. 
An example of the latter construction will be found in 
Fig. 17. 



SOME MISCELLANEOUS ITEMS. 

Lintels. — Concrete lintels and beams are fast super- 
seding those made of stone and wood. Lintels are 
generally cast and then fixed. 



474 



CEMENTS AND CONCRETES 



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A Spiral Staircase built on the Henneblque 
principle. 



HOW TO USE THEM 475 

Concrete Walls. — Many ingenious plans have been 
introduced as substitutes for wood framing for retain- 
ing concrete while constructing walls and partitions. 
The most simple method is as follows : Cast a number 
of concrete angle slabs with an L section, and then 
place them level in contrary directions, thus { [y 
spaced to the width of the proposed partition or wall 
until the desired length of wall is completed, and fill 
the openings with rough concrete. When set, place 
another row on this (taking care to break the joints by 
overlapping), and so on, until the desired height is 
obtained. Concrete for walls formed in situ should be 
deposited in layers, taking care that each layer is thor- 
oughly rammed and keyed, as described under the 
heading of ^'Ramming." A suitable finish for ordi- 
nary purposes, for rough walls built in situ, may be 
obtained \)y ^' rough trowelling." This is done by 
first gauging 1 part of Portland cement, 1 part of old 
lime putty, and 2 parts of sand. The adding of lime 
renders the stufi^ more plastic and easy to work, with- 
out decreasing the impermeability of the work. This 
''limed cement" is applied with a hand-float, and is 
thoroughly worked into the crevices of the concrete, 
but leaving no body on the surface. The surface is 
then finished by brushing with a wet stock-brush. The 
walls should be well wetted before the stuff is applied. 

Strong Booms. — Concrete is frequently employed in 
the construction of strong-rooms that are situated 
underground, and are rendered damp-proof as well as 
burglar-proof, which is useful for the storage of docu- 
ments. 

Concrete Coffins and Cementation. — The great im- 
provements in the manufacture of Portland cement 



476 CEMENTS AND CONCRETES 

during the last decade has so cheapened and improved 
the quality as to bring it more and more to the front 
as one of the most useful and important materials for 
a variety of purposes. One of the latest uses found for 
it is in the construction of coffins, by the author, whose 
invented and registered idea was that such a coffin, 
made of specially prepared metallic concrete, would 
be impermeablCj and practically indestructible, and 
that it would obviate the danger of spreading the 
poisons of disease by preventing the escape of noxious 
gases. The lid having a strong piece of plate glass 
embedded in the concrete, and directly over the face, 
enabled the mourners to see the features of the depart- 
ed. The edge of the open coffin had a sunk groove, 
and the lid a corresponding projection, only smaller, 
to allow for a coat of fine cement. When the joints 
were bedded and pressed together until the excess ce- 
ment oozed out, the coffin was hermetically sealed. 
The coffin should be left uncovered by cement for 
identification, and so that friends could view it until 
the time of removal to the cemetery. The face could 
then be covered with quick-setting cement, which, join- 
ing with the other portion of cement, would perma- 
nently embalm the body, which would further be pro- 
tected by fixing the lid in a similar way. If the prop- 
erties of this class of coffin are taken into considera- 
tion, the expense will be comparatively less than that of 
wood. If expense is not a special consideration, the 
coffin can be enriched with armorial bearings or other 
devices. The concrete may also be polished like real 
granite. One objection was raised as to the weight, 
but the old stone coffins and those of oak lined with 
lead were also heavy. Besides, the weight would ht 



HOW TO USE THEM 477 

a protection against body-snatchers, and bearing in 
mind that a coffin is only moved about once in a life- 
time, or rather at death, the question of weight is un- 
important. Cementation, from a sanitary point of' 
view, would be equal if not superior to cremation. In 
case of an epidemic, the coffins could be cemented at 
once, and stacked in the cemetery until graves or vaults 
v/ere prepared for them. It may be safely said that it 
is a clean, safe, effectual, rapid and sanitary method 
of disposing of the dead. If their manufacture should 
not cause any great amount of extra employment for 
plasterers, the latter can at least make their own cof- 
fins, in frosty weather, when most works are stopped, 
and they could use them as baths during their life- 
time. 

Stonette. — Stonette is a composition of Portland ce- 
ment and fine aggregate, to imitate any kind of stone, 
and so made that it can be carved the same as natural 
stone. The Portland cement must be thoroughly air< 
slaked, finely sifted, and gauged with the natural ag- 
gregate in the proportion of 2 of cement to 7 of ag- 
gregate. The aggregate is composed of finely crushed 
natural stone, the same as that to be imitated. This 
should be passed through a fine sieve. It is necessary, 
when imitating some stones, to add a small portion of 
oxide to counteract the color of the cement. If a very 
white stone is being imitated, the addition of a small 
proportion of whiting or French chalk or well-slaked 
white limestone, is necessary to obtain the desired 
color. The material should be gauged stiff, and then 
well rammed into the mould. The carving is best done 
while the cast blocks are green. 

Tile Fixing. — Tile fixing is in some places a sepa^ 



478 CEMENTS AND CONCRETES 

rate branch of the building trade^ but it is generally 
recruited from the ranks of plasterers, and in some 
districts it is done by plasterers. As regards the pro- 
cess of placing the tiles, it is best to work from the 
centre of the space, and if the design be intricate, to 
lay out a portion of the pavement according to the 
plan, upon a smooth floor, fitting the tiles together 
as they are to be laid. Lines being stretched over the 
foundation at right angles, the fixing may proceed, 
both the tiles and the foundation being previously 
soaked in cold water, to prevent the too rapid dry- 
ing of the cement, and to secure better adhesion. The 
border should be left until the last. Its position and 
that of the tiles are to be obtained from 'the drawing, 
or by measuring the tiles when laid loosely upon the 
floor. The cement for fixing should be mixed thin, in 
small quantities, and without sand. It is best to float 
the tiles to their places, so as to exclude air, and fill 
the spaces between them and the foundation. For fix- 
ing tiles in grate cheeks, sides and backs of fire-places, 
etc., equal parts of sand, plaster and hair mortar may 
be used. These materials are sometimes mixed with 
hot glue to the consistency of mortar. The tiles should 
be well soaked in warm water. Keen's or other white 
cements are used as fixing materials for wall tiles, neat 
Portland cement (very often killed) being generally 
used for floor work. Tiles may be cut in the follow- 
ing manner : Draw a line with a pencil or sharp point 
where the break is desired, then placing the tile on a 
form board, or embedding it in sand on a flagstone, 
tap it moderately with a sharp chisel and a hammer 
along the line, up and down, or scratch it with a file. 
The tile may then be broken in the hand by a gentle 



HOW TO USE THEM 479 

blow at the back. The edges, if required, may be 
smoothed by grinding or by rubbing with sand and 
water on a flat stone. Tiles may also be sawn to any 
desired size. Cement should not be allowed to harden 
upon the surface of the tile if it can be prevented, as 
it is difficult to remove it after it has set. Stains or 
dirt adhering to tiles may be removed by wetting with 
diluted muriatic acid ("spirits of salts"), care being 
taken that the acid is all wiped off, and, after wash- 
ing, the superfluous moisture must be wiped' off with 
a clean, dry cloth. In order to obtain a sound and 
straight foundation, which is imperative for good per- 
manent tile fixing, the substratum, Vv^hether on walls or 
floors, should be composed of Portland cement gauged 
with strong sand or similar aggregate in proportion 
of 1 of the former to 3 of the latter. The surface must 
be ruled fair and left rough, so as to form a fair bed 
and key for the fixing materials and tiles. 

Setting Floor and Wall Tile. — As this work properly 
belongs to the plasterer, where no regular tile setter is 
available, I have thought it proper to publish the fol- 
lowing instructions for doing this work, which are 
taken from a treatise prepared for the Tile Manufac- 
turers of the United States. This treatise, in pamphlet 
form, was intended for distributix)n among buyers and 
workers in tiles, and the directions and suggestions 
laid down in it are of the best, and quite suited to the 
wants of the workingmen : 

Foi,tndations. — A good foundation is always neces- 
sary, and should be both solid and perfectly level. Tile 
should always be laid upon concrete foundation, pre- 
pared from the best quality of Portland cement and 
clean, sharp sand and gravel, or other hard material. 



480 CEMENTS AND CONCRETES 

(Cinders should never he used, as 'they have a tendency 
to destroy the life of the cement and cause it to dis- 
integraie.) A foundation, however, may also be formed 
of brick or hollow tile embedded solidly in and covered 
with cement mortar. Concrete should be allowed to 
thoroughly harden before laying the floor, and should 
be well soaked with water before laying the tile. 

Lime mortar should never be mixed with concreting. 

Concrete should consist of one part Portland cement, 
two parts clean sharp sand, two parts clean gravel, 
and thoroughly mixed with sufficient water to form a 
hard, solid mass when well beaten down into a bed, 
which should be from 2^4 inches to 3 inches thick. If 
the concrete bed can be made over three inches in 
thickness, the concrete can then be made of one part 
Louisville cement^ one part clean sharp sand, one part 
clean gravel and thoroughly mixed w^ith sufficient wa- 
ter, as above described. 

For Floors. — The surface of the concrete must be 
level and finished to within one (1) inch of the fin- 
ished floor line, when tile ^2 inch thick is used, which 
will leave a space of % inch for cement mortar, com- 
posed of equal parts of the very best quality Portland 
cement and clean sharp sand. The distance below 
the surface of the finished floor line, however, should 
be governed by the thickness of the tile. 

For Wood Floors. — When tiles are to be laid on wood 
flooring in new buildings the joists should be set five 
inches below the intended finished floor line and spaced 
about 12 inches apart and thoroughly bridged, so as to 
make a stiff floor^ and covered with one-inch boards 
not over six inches wide (boards three inches wide 
preferred); and thoroughly nailed, and the joints % 



HOW TO USE THEM 



481 



inch apart to allow for swelling. (See No. 31.) (A 
layer of heavy tar paper on top of wood flooring will 
protect the boards from the moisture of the concrete, 
and will also prevent any moisture from dripping 
through to a ceiling below.) 



FLOon Lwe 




Fig. 31. 



In Old Buildings. — Cleats are nailed to joists five 
inches below the intended finished floor line, and short 
pieces of boards % inch apart fitted in between the 




FLOOR um 



~Tll£ 

-cojvcnsTs 

SUB-FLOOa 
- CL£ATS 



BRlOGWO 
-JOiST 



Fig. 32. 

joists upon the cleats and well nailed, and the joists 
thoroughly bridged. The corners on the upper edge 
of the joists should be chamfered off to a sharp point 
(see Fig. 32), as the flat surface of the joists will give 
an uneven foundation. When the strength of the 
joists will permit, it is best to cut an inch or more off 



482 



CEMENTS AND CONCRETES 



the top. (AYhere joists are too weak, strengthen by 
thoroughly nailing cleats six inches wide full length 
of joists.) When the solid wood foundation is thus 
prepared, concrete is placed upon it as above directed. 
Where Steel Beams and hollow tile arches are used, 
frequently very little space is left for preparing a 
proper foundation for setting tile, as the rough coating 
is usually put in by the hollow tile contractor to pro- 
tect his work, but this covering should ahvays conform 




csneum 



rARCH 



Fig. 33. 

to the requirements for a solid tile foimdation. Should 
this not be the case, the tile contractor should remove 
sufficient of the covering to allow him to put down a 
foundation that will insure a satisfactory tile floor. 
(Cinders, lime, mortar or inferior material must never 
be used.) 

Tlie tops of iro^i hemns should he from three to four 
inches helow ihe finished floor line, to prevent floors, 
when finished, shoiving lines of the beams. 

For Hearths.— The foundation for hearths should be 
placed upon a brick arch, if possible, to ensure perfect 
fire protection, and then covered with concrete in the 
same manner as directed for tile floors. If placed 
upon a sub-foundation of wood, the concreting should 
be at least six inches thick. (See Figs. 34 and 35.) 



HOW TO USE THEM 



483 




TKW^^VTT/ '/ '/ 7 '-■ y /'flW^/fl BOARD FLOOR 



m 






BRICK WAU. 



BRICK ARCH 




—JOIST 



y///yy../^/yyyy^^i af^.:^//////,y^///^ ^y^^^^^ 



Fig. 34. 




noAn o FLoon 



BRICK W/»LU 



y////J^//y///liiiUik^//,J////7 



-JOIST 



'/m//////h7 



Fisr. 35. 



484 



CEMENTS AND CONCKETES 



For TFaZJs.— When tiles are to be laid on old brick 
walls the plaster must be all removed and the mortar 
raked out of the joints of the brick work to form a key 
for the cement. On new brick walls the points should 
not be pointed. When tiles are to be placed on stud- 
ding, the studding should be well braced by filling 
in between the studding with brick set in mortar to the 
height of tile work (see Fig. 36) ; or brick work may be 
omitted and extra studding put in and thoroughly 



-^STVOOfNC 




Fig. 36. 



bridged, so as to have as little spring as possible, and 
this studding then covered with sheet metal lathing. 
(See Fig. 37.) {Tile must never be placed on ivood lath 
or on old plaster.) The brick walls must be well wet 
with water and then covered with a rough coating 
of cement mortar, composed of one part Portland ce- 



HOW TO USE THEM 



485 



Ment and two parts clean sharp sand. When tiles are 
placed on metal lathing, hair should be mixed with the 
cement mortar to make it adhere more closely to the 
lath. The cement mortar should be % inch thick, or 
sufficient to make an even and true surface to within 
one (1) inch of the intended finished surface of the 
tile, when tile ^^ inch thick is used, which will allow 



-STUDDINS 




Fig. 37. 



a* space of % inch for the cement mortar, composed as 
above for. rough coating the walls. The face of the 
cement foundation should be roughly scratched and 
allowed to harden for at least one day before com- 
mencing to lay the tile. If any lime is mixed with the 
cement mortar for setting the tiles^ it should never 
exceed 10 per cent., and great care must be used to 
have the lime well slaked, and made free from all 



486 CEMENTS AND CONCRETES 

lumps by running through a coarse sieve, in order to 
guard against "heaving" or ''swelling," and thus 
loosening or "lifting" the tiles. 

Important. — The foundation for both floor and wall 
tiling should be thoroughly brushed, to remove all dust 
and small particles adhering to it, and then well wet 
before putting on the cement mortar. To ensure a 
perfect bond it is best to coat the foundation by brush- 
ing over it pure cement mixed in water. 

Cement, — The very best quality of Portland cement 
should always be used for setting either floor or wall 
tile and for grouting the floors, and the very best 
quality of Keene's Imported Cement for filling the 
joints in the wall tiling. 

Sand. — Clean, sharp grit sand, free from all salt, 
loam or other matter, and perfectly screened before 
mixing with the cement, should always be used. 

Mortar. — For floors or vitreous tiles, should be com- 
posed of equal parts of cement and sand, and for wall 
tiles one (1) part of cement n.nd two (2) parts sand. 
The mortar should not be too wot, but should be rather 
stiff, and should always be used fresh, as mortar, when 
allowed to set before using, loses a portion of its 
strength. 

SoaMng. — Tiles must always be thoroughly soaked 
in water before setting^ which makes the cement unite 
to the tiles. 

Tlie Tiles for the Floors are first laid out to ascer- 
tain if they are all right and compared with the plan 
provided for laying the floors. Strips are then set, 
beginning at one end of and in the centre of the room, 
and level with the intended finished floor line. Two 
sets of guide strips running parallel about 18 to 30 



HOW TO USE THEM 



487 



inches apart should be set first. (See Fig. 38.) The 
mortar is then spread between them for about six to 
ten feet at a time, and level with a screed notched at 
each end, to allow for the thickness of the tiles. The 
tiles are placed upon the mortar, which must be stiff 
enough to prevent the mortar from working up be- 






I f I I I I I I," I 

t ,'.. I , I. . ■'■ V < 




Fig. 38. 

tween the joints. The tiles are to be firmly pressed 
into the mortar and tamped down with a block and 
hammer until they are exactly level with the strips. 
"When the space between the strips is completed, the 
strips on one side of the tile is moved out 18 to cJO 
inches and placed in proper position for laying an- 
other section of tile, using the tiles which have been 



488 CEMENTS AND CONCRETES 

laid for one end of the screed^ and the laying of the 
tile continued in the same manner until the floor is 
finished. When the cement is sufficiently set^ which 
should be in about two days, the floor should be well 
scrubbed with clean water and a broom, and the joints 
thoroughly grouted with pure cement (mixed with 
water to the consistency of cream). As soon as this 
begins to stiffen, it must be carefully rubbed off with 
sawdust or fine shavings and the floor left perfectly 
clean. 

Ceramics. — The foundation and cement mortar for 
ceramics are the same as for plain or vitreous floors, 
and the guide strips used in the same manner. The 
cement mortar is then spread evenly and the tile sheets 
laid carefully on it with the paper side up. After the 
batch is covered, the tile setter should commence to 
press the tile into the mortar, gently at first, firmly 
afterwards, using block and hammer, thus leveling 
the tile as correctly as possible. The tile should be 
beaten down until the mortar is visible in the joints 
through the paper ; however, without breaking it. The 
paper is then moistened, and after it is well soaked 
and can be easily removed, it is pulled off backwards, 
starting from a corner. After removing the paper, the 
tile should be sprinkled with white sand before fin- 
ishing the beating, so that the tiles will not adhere to 
the beater, owing to the paste which is used in mount- 
ing them. Corrections of the surface are then made 
by leveling it with block and hammer. The filling of 
the joints and cleaning of the surface is a delicate op- 
eration, as the looks of this work depends largely upon 
it. The joints are to be filled with clean Portland 
cement mixed with water. This mixture is forced into 



HOW TO USE THEM 



489 



the joints with a flat trowel (not with a broom, which 
often scrapes out the joints). After the joints are 



— SC/?££0 




^CONCRETB 
Fig. 39. 

filled, the surplus cement is removed from the sur- 
face by drawing a wet piece of canton flannel over it. 




Pig. 40. 



This piece of cloth must be washed out frequently with 
clean Avater. After the floor is cleaned, it should be 



490 



CEMENTS AND CONCRETES 



allowed to stand for a day or two, when the whole 
floor is to be rubbed with sharp sand and a board of 
soft Inmber. This treatment, which the last traces of 
cement, is preferable to the washing off with an acid 
solution, as it will not attack the cement in the joints. 
In laying the tile sheets on the cement, care should be 
taken to have the widths of joints spaced the same as 
the tile on the sheets to prevent the floor having a block 
appearance. 



ceMt«jT 

SACMIN* 



CufOC STRIP 




Fig. 41. 



The Tiles for the Walls or WaiTiscoting are first laid 
out and compared with the plan provided for setting 
them. Guide strips are then placed on the wall paral- 
lel and about two feet apart, the bottom one being so 



HOW TO USE THEM 491 

arranged as to allow the base to be set after the body 
is in place. (See Fig. 40.) When a cove base is used 
it may be necessary to set it first, but in all cases must 
be well supported on the concrete. (See Fig. 41.) The 
strips must be placed plumb and even with the intend- 
ed finished wall line. The method of setting wall tile 
is governed to some extent by the conditions of the 
wall on which they are to be set, and must be decided 
by the mechanic at the time, which process he will 
use, whether buttering or floating-, as equally good 
work can be done by either, by following the instruc- 
tions, as stated below. 

Floating Wall Tile. — The mortar is spread between 
the guide strips for about five feet at a time and lev- 
elled with a screed notched at each end to allow for 
the thickness of the tile. (See Fig. 39.) The tiles are 
placed in position and tamped until they are firmly 
united to the cement and level with the strips. When 
the space between the strips is completed, which should 
be one side of the room, the strips are removed and 
the work continued in the same manner until com- 
pleted. When the tiles are all set, the joints must be 
carefully washed out and neatly filled with thinly 
mixed pure Keene's Cement, and all cement remaining 
on the tile carefully wiped off. 

Buttering Wall Tiles.)i — The cement mortar is spread 
on the back of each tile, and the tile placed on the 
wall, and tapped gently until firmly united to the wall 
and plumb with the guide strips. When the tiles are 
all set, the joints must be carefully washed out and 
filled with Keene's Cement, and the tiles cleaned as 
directed above. 

When fixtures of any kind are to be placed on the 



492 CEMENTS AND CONCEETES 

tile work^ sucli as plumbing in bathroom, provision 
shonlcl be -made for them by fastening wood strips on 
the wall before the rough or first coating of cement 
mortar is put on, the strips to be the same thickness 
as the rough coating. The tiles can be placed over 
the strips by covering them with cement mortar, and 
when thoroughly set, holes can be bored in the tiles for 
fastening the fixtures without injuring the tiling. 

Heartli and Facing Tile are set in the same manner 
as for floors and walls. 

Cleaning. — It is absolutely necessary to remove with 
sawdust, and afterwards with a flannel cloth and wa- 
ter, all traces of cement which may have been left on 
the surface of the tile, as it is hard to remove after it 
is set. 

After thoroughly cleaning the floor, it should be 
covered with sawdust and boards placed on the floor 
for several days where there is walking upon it. 

A white scum sometimes appears on the surface of 
the tile, caused by the cement. This can generally be 
removed by washing frequently with plenty of soap 
and water. Tf this does not remove it, then use a weak 
solution of 15 parts muriatic acid and 85 parts wa- 
ter, which should only be allowed to remain on the 
tile for a few minutes, and then thoroughlv washed 
off. 

Cutti7ig of Tile.— When it is found necessary to cut 
tile the following directions are given : 

Tools.^— The chisels used should be made of the best 
tool steel, and should always be sharp. They should 
be of small size, the edge not being wider than one- 
fourth inch. The hammer should be light, weighing 
about six ounces, having a slender handle. After the 



HOW TO USE THEM 493 

exact shape of the tile has been determined, lines 
should be drawn on the surface of the tile with a lead 
pencil, giving the exact direction of the cut desired. 
This line should be followed with the chisel, which is 
held at right angles with the surface, the hammer 
giving the chisel sharp, decisive raps. After the line 
has been repeatedly traversed with the chisel, a few 
sharp blows against the back of the tile opposite the 
mark on the face will break it at the place thus 
marked. 

To cut glazed or enamel tiles, they should be 
scratched on the surface with a tool at the place where 
it is desired to break them, and then gently tapped 
on the back opposite the scratch. 

Caution should be used not to allow any one to 
walk upon or carry anything heavy over the floor, or 
have any pounding about wall work for several days, 
or until the tiles are firmly set. Unless these precau- 
tions are taken it will be impossible to guarantee a 
first-class job. Tile work is frequently condemned 
when the fault lies with the rush of other contractors to 
finish their work. 

Laying Tile on Wood. — A new material called 
''Monolith/' manufactured by The Wisconsin Mantel 
& Tile Co., that enables the workman to lay tiles on 
a wooden floor. There are many places where tile 
could be used, but on account of the added weight to 
the floor by the use of cement, concrete foundation, it 
is impracticable to lay in many places, but by the use 
of Monolith, the only weight that is added is the tile 
itself and the Monolith bed it is laid in. Both ma- 
terials are only five-eighths of an inch in thickness 
when laid. 



494 



CEMENTS AND CONCRETES 



/' 






v: %\ 







HOW TO USE THEM 495 

The illustration, Fig. 42, shows the method of laying 
the tile. The paper to which the small pieces of tiles 
are glued is seen on top of tiles. The dark part shows 
the patent cement, or Monolith. 

I show herewith^ at Nos. 43 and 44, twelve designs 
for deco/ative borders of various kinds, and in 45 
and 46 I show two designs well suited for vestibules, 
store entrances or for hearths in fire-places. 

Good Concrete. — In determining the proportions of 
the aggregates and cement for a certain piece of work, 
it is necessary usually to take samples of the broken 
stone (or gravel) and sand which are most available 
to the site and make measurements of the percentage 
of voids in the stone which must be filled by the sand 
and the percentage of voids in the sand which must 
be filled by the cement. This is done by taking a 
cubic foot box and filling it with broken stone in a 
thoroughly wet state. The box is then filled with as 
much water as is required to completely fill it, in addi- 
tion to the stone, which upon being poured off gives 
the relation between the volume of the voids and the 
volume of the stone. The required amount of local 
sand thus determined is then measured out and placed 
in the box with the stone in a damp state. Water is 
then used to determine the percentage of voids left in 
the sand, w^hich gives the approximate amount of 
cement required, although an excess of cement is al- 
most invariably used. Engineers everywhere differ 
regarding the best proportion to be used, but in gen- 
eral the above test^ roughly made, will determine it 
well enough. The proportions which are most univer- 
sally used are as follows : 1 cement, 2 sand, 4 broken 
stone ; where extremely strong work is desired. Tests 



496 



CEMENTS AND CONCRETES 



.Bdbd5£> No, 411 




Border No. 412 



^wTSTv;: yftii ri- 


n rivfii 1 1 r r 11 n 1 1 i it j.i rri m 


n 1 M Mf 1 M 1 ri I n-i 


r ■'! f I'l ' ~ 


isWvUOCWvWX 


? Ci rt 1 1 i 1 1 ij J ,1 ji ^ ^ V 't^ * u r 


xxXOuOCJOOOOOtjOOC 


iujS 






iSWrVjPiWrV*^ 


r-ffi^ 


¥r'rVPif!i^iyi?r*E'r?iVi^'iiV?) 


iVrfMWrVfrVi?!' 


K^^P^fW^^^^ 


rrn YrT^TTYTTTltYrTVTTTTTrrT 


AWvwXPtwC^ 


mimRi^miT] 


-f+rr rf^i^-f-Vrrt fh'rrm-y f- r rr r^- 


'rt-rii-f-f f i^*'!*'7!'-v\^ 





Border No. 413 




Border No 4)4 




Border No. 415 




Border No 418 




Decorative Borders in Round, Square and One Ipcli 
Hexagons of Various Colors. 



Fig. 43. 



HOW TO USE THEM 



497 




16" Wide 



SoRDER No., 548:- 



^mdeam 







n ,MIII '»!1-p-*-' ij :|l i !i-h-r| 



LL LLi U 





^^K^ 



A Series of Borders in Square Tiles, Each ia a 
Variety of Colors. 



Fig. 44, 



498 



CEMENTS AND CONCRETES 



show that a 6-inch thickness of 1-2-1 concrete properly 
made is waterproof up to about 50 pounds to the square 
inch. This concrete is frequently used for facing- 
dams. 1-3-6 is the proportion generally used for the 
interior of dams and large structures. It is entirely 
suitable for large foundations.^ 1-4-8^ is frequently 
used for foundation work^ and when properly mixed 




Fig. 45. 



makes good concrete, although it is about the limit 
of what is considered good work^ and would not be 
suitable for very important structures. 1-5-10 is equal 
to any concrete made with natural cement. It is a 
well-known fact that the volume of concrete when 
mixed with water is somewhat less than the volume of 
the aggregate and cement before mixing. The con- 
tractors' rule is that the volume of mixed concrete is 



HOW TO USE THEM 



499 



equal to the volume of the stone plus one-half to one- 
third the volume of sand. 

There has been much discussion among engineers 
and others as to the amount of water that should be 
added to the aggregates and cement for making the 
best concrete, and while it is not the purpose of this 
paper to enter into this controversy, it might be said 
that the modern tendency is toward wet concrete. The 
old way was to add just enough water so that when all 









^^M 








^i 




..^g^nvmim^ ■ owfj*^ ^ ^ 


V- '■ >. 










r^'''^rww^iiSif"<^'^^'w^'^' 


*©p^"'^»'^ 








Hl^^r^w^^w^^ 


i 


■^— Gf ■ ^A<Sr ^CA.< 


^S ■^ 


^m Hmn 


HPpr-'k 


BSS^PSSP^SSi^jft' ^' K^t'-™-"i''^f; 'i'!.iV''i;:ffi»Kw^ 


\ V > < 

y — \ y — ^ 




«S^^ 


H^ 




i 




^^Ji^\^>.A.J^.^.^M,.A^A. 




k^ 


^ 


a9 B^l 




m 


maMMU 


B 


B^B^taHfaB^BKdtiWi&ri^ 


i 





Fig. 46. 



the concrete was in the form and tamped, it would 
?how moisture on the surface. The tamping is a very 
important part of the operation, and the quality of 
the work is dependent upon how well this is super- 
intended, as unless it is well and thoroughly done the 
concrete is liable to be honeycombed and imperfect, 
especially near the forms. With the growth of the 



500 CEMENTS AND COXCEETES 

use of concrete the old method of putting it in the 
forms nearly dry and depending on tamping to con- 
solidate it has been more or less abandoned, and tlie 
more modern way is to put the concrete in quite wet, 
as less tamping is required and much labor and ex- 
pense saved. One of the great objections to this 
scheme is that if care is not taken the water will tend 
to wash the cement from the stone and sand; in other 
words, unmix it. However, it may be said that it 
is now generallv understood that rather wet concrete 
properly handled makes better work. The amount of 
water to be added to the aggregates and cement va- 
ries from 1 water to 3 cement by measurement to 12 
per cent of water by weight. Mr. Carey, of New- 
haven, England, says that 23 gallons water per cubic 
yard of cement was the best mixture. Quite frequent- 
ly salt water is used in mixing concrete in cold weather 
to prevent freezing, and it seems to have no ill effects 
on the resulting mixture. 

Reinforced Concrete. — ^Up to the last few years the 
use of concrete as a building material was chiefly con- 
fined to the construction of foundations, piers, reser- 
voir dams and similar purposes, in which the stresses 
to be met were almost entirely simple pressures. In- 
deed, even fifteen years ago, many engineers looked 
askance on the use of concrete for arches, considering 
it for this purpose much inferior to brick. Much of 
the caution shown in extending the use of this valua- 
ble material doubtless arose from the frequency with 
which concrete masonry exhibited unsightly cracks, 
due largely to the material being allowed to get too 
dry while hardening. At the same time, careful ex- 
amination has shown that cracks of the same char- 



HOW TO USE THEM 501 

acter are common in masonry of all kinds, but are 
unnoticed, because they follow the regular joints of 
the structure ; whereas, on the smooth uniform sur- 
face of the concrete, cracks of much less significance 
are immediately visible. 

The plan of reinforcing the material with metal, of 
which several systems have been introduced during 
the last four years, has greatly extended the possible 
use of concrete ; and it appears that in many cases a 
reinforced concrete bridge may compete, even in first 
cost, with a steel girder ; while as regards upkeep, it 
haSj of course, many advantages. Small bridge cul- 
verts of this material were extensively used by Rus- 
sian engineers in building the Manchurian Railway. 
For openings of some 7-foot span, flat slabs of con- 
crete reinforced with rails were used, the thickness 
being 814. inches. A similar system was used for spans 
up to 21 feet, the concrete, however, being thickened 
at the center as the span increased, the depth at this 
point being 2 feet 6^ inches for the 21-foot span, and 
proportionately less for smaller openings. The thick- 
ness at the bearings was, however, the same in all 
cases, viz., 8Vt inches. The line was thrown over the 
spans as little as seven days after completion. The 
concrete consisted of one part cement, two sand and 
five broken stone. The system in this case had great 
advantages, as stone for inasonry was unobtainable, 
and could, moreover, only be used for arches, which 
would have necessitated the use of higher embank- 
ments than were required with the ferro-concrete, used 
as described. Much larger spans have, of course, been 
built than those mentioned. One, of 153-foot span, 
carrying four main line tracks, has recently been 



502 CEMENTS AND CONCRETES 

built for the Lake Sliore and Michigan Southern Rail- 
road, while Mr. Edwin Thacker, M. Am. Soc. C. E., 
states he considers the system feasible for spans up 
to 500 feet, and has actually got out designs for a 
span 300 feet the cost comparing favorably with that 
of a steel bridge. 

One great drawback to the extension of the system 
lies in the difficulty in proportioning structures thus 
built in a thorouo'hlv rational manner. In the case of 
steel bridges certain simple assumptions as to the 
elasticity and strength of the material suffice. These 
assumptions are doubtless not absolutely exact, but are 
sufficiently near the truth for practical purposes. The 
elastic properties of concrete are, however, very dif- 
ferent from those of steel; Hooke's law is not even ap- 
proximately correct, and, moreover, the material al- 
ways takes a permanent set when first loaded. The 
true distribution of the stress and strain on a concrete 
beam is thus a much more complicated matter than it is 
in the case of a steel joist, in which it is permissible, 
within working limits of stress, to assume the accuracy 
of Hooke's law. The assumption generally made in 
the case of ferro-concrete is that plane sections of a 
concrete beam remain plane after bending. This pos- 
tulate is, of course, that commonly made in propor- 
tioning steel work ; and in the latter case, stress being 
proportional to strain, the usual formula for the work- 
ing strength of beams is readily reduced. In the case 
of concrete, however, the stress-strain curve is much 
more complex. Nevertheless, M. Considere has shown 
that by making experiments on concrete in simple ten- 
sion and compression, and plotting the corresponding 
stress-strain curves, it is possible to deduce from these 



HOW TO USE THEM 503 

with fair accuracy the load-deflection curve of a ferro- 
concrete beam. 

This method, though logical, leads, however, to no 
simple formula for the strength; and in applying this 
method the working load of any particular concrete 
beam would have to be deduced by the tedious proc- 
ess of scaling off the stress-strain curves at a num- 
ber of points, and combining the results. A further 
question arises as to whether this stress-strain curve 
should be the initial stress-strain of the concrete, or 
that obtained after repeated loadings. Probably the 
latter is the best to choose, but in that case it by no 
means follows that the metal reinforcement is free 
from initial stresses when the load is applied to the 
beam ; and if the metal is subject to initial stress, it is 
obvious that similar ones must exist in the concrete. 
In fact, M. Considere has shown that this is necessarily 
the case in any circumstances, since, if the concrete is 
allowed to harden under water, it tends to expand, 
and this expansion is resisted by the metal reinforce- 
ment. If, on the other hand, the hardening takes 
place in air the concrete tends to contract ; and this 
contraction being again resisted by the metal, a series 
of fine hair cracks are produced which, visible at low 
loads, are readily detected on the tension side of a 
heavily loaded ferro-concrete beam. 

In view of the uncertainties introduced by the dif- 
ferent factors above mentioned, it is really questionable 
whether, after all^ the theoretically objectionable for- 
mula of M. Hennebique is not as good as any other. 
The latter all involve a preliminary calculation of the 
position of the neutral axis, which varies with the per- 
centage of metal used; and with the type of stress- 



504 CEMENTS AND CONCRETES 

strain curve assumed for the concrete; and also with 
the maximum stress at any particular section. Thus, 
in a centrally-loaded beam, its position at the ends is 
entirely different from what it is at the centre. M, 
Hennebique, on the other hand, makes no attempt to 
locate this neutral axis, and simply assumes that one- 
half of his beam resists compression, and that the 
stress is uniformly distributed over this half. The 
moment of this compression about the centre of the 
section equates to half the moment due to the load, 
and the other half of the moment due to the load he 
equates to the moment about the centre of the section 
of the tensile stress on the metal reinforcement. The 
working strength of concrete in compression, he takes 
as 350 pounds per square inch, and neglects entirely its 
strength in tension. The working tensile stress on the 
steel reinforcement he takes as 14,000 pounds per 
square inch. This method is, of course, totally illogi- 
cal, yet many thousand cubic yards of ferro-concrete 
have been successfully designed on these lines; and a 
comparison of the strength of ferro-concrete beams 
as calculated by this formula, and by those of a more 
rational type, shows very little difference between the 
two for a considerable range of metal to concrete. On 
the other hand, it must not be forgotten that formulae 
which are non-rational in form are always risky when 
applied to extreme conditions. 

Concrete being as weak in shear as in tension, pro- 
vision is also required to take the shearing stresses. 
Some American designers have to this end patented, 
special forms of reinforcement bar, in which each main 
tension bar has projecting upward from the ties in- 
clined at an angle of 45 degrees. These extend to the 



HOW TO USE THEM 505 

top of the bar and take the tensile stresses arising 
from the shear. The corresponding compressive stress 
at right angles to this is carried by the concrete. The 
system is doubtless efficient^ and on large spans, where 
weight must be reduced to a minimum it may have 
some advantage; but in work of ordinary proportions 
it seems to be little superior to the Hennebique sys- 
tem, in which the necessary strengthening is provid- 
ed by stirrups of flat iron bent into a U shape. The 
main reinforcing bars rest in these stirrups at the 
lower ends. The spacing of the stirrups depends upon 
the ''web stresses" to be taken, which can easily be 
calculated by assuming the reinforced beam to be a 
latticed girder, the lower chord of which is represented 
by the metal reinforcement, the upper one by the centre 
of the compression half of the beam, while the stirrups 
represent vertical ties, which may be taken as con- 
nected together at top and bottom by inclined imag- 
inary struts. The advantage of this simple method of 
reinforcing for shear lies in the possibility of using 
common rolled sections for the whole of the rein- 
forcement. 

M. Hennebique constructs most of his ferro-concrete 
work on the monolithic system, girders, piers, columns 
and floors being solidly connected together. It is, 
therefore, necessary to provide for the reversed bend- 
ing moments over the point of support, which is done 
by bending up half of the total reinforcement bars, 
so that the ends of the span are close to the upper 
surface of the beam, and thus in a position to take 
the heavy tensile stresses which ensue at these points 
when the monolithic system of construction is fol- 
lowed. The exact calculation of the reactions and 



506 CEMENTS AND CONCRETES 

bending moments here is impracticable, if not actually 
impossible; and those engineers who attach much im- 
portance to having all structures statically determinate 
will doubtless object to the plan, but experience shows 
that the advantages gained are very considerable. The 
structure then resists as a unit; and in particular its 
rigidity is marvelous. 

Some comparative tests on this point, made by the 
Railway Company, showed that with a ferro-concrete 
floor subjected to blows four times as heavy as were 
applied to an equivalent floor constructed of brick 
arches on steel joists, the deflection was only one- 
seventh as great. 

The extreme rip^iditv attainable with the monolithic 
system of construction was also very evident in the 
case of the large Plennebique bridge at Purfleet. Since 
a structure fails bv strain rather than bv stress, the 
small deformation noted with ferro-concrete are evi- 
dent that as an average the material is relatively lit- 
tle tried by the loads carried. It must, however, be 
admitted that this low average strain is cjuite com- 
patible with extremely severe strain at particular 
points ; but it is, of course, the business of the designer, 
by suitably disposing his material to avoid these pos- 
sible local abnormalities. 

Occasionally, doubts have been expressed as to 
whether the metallic reinforcement may not suffer from 
corrosion as time g'oes on. This would be extremelv 
dangerous if it occurred, since the metal being out of 
sight, its loss of strength might remain undetected un- 
til, some day, the structure might fall under its ordi- 
narv working load. Fortunateh^ much evidence is 

*J C_5 €-■■ 7 

available to the effect that steel or iron thoroughly 



HOW TO USE THEM 507 

imbedded in concrete is permanently protected from 
rust. Americans, indeed, are so positive on this point 
that they have recently constructed a number of reser- 
voir dams in ferro-concrete. In some cases these have 
"been arched, but in others they have been straight. 
The cross-section in the latter case is generally a hollow 
triangle, the sides of which are connected together by 
diaphragm walls from point to point. The dam is also 
anchored to its site, though generally the weight pro- 
vided is sufficient to make the structure safe against 
overturning, quite apart from the help received from 
the anchor-bars. 

Progress in the use of reinforced concrete has been 
somewhat slow in England. The railway engineers, in 
view of their enormous responsibilities, have not un- 
naturally hesitated to adopt a material in which it was 
impossible to calculate the strength with accuracy, and 
of which experience as to its reliability was very re- 
cent. In the larger cities, moreover, its use has, quite 
apart from this, been restricted by the inelastic na- 
ture of the building regulations, which have been 
reached upon the assumption that finality had been 
reached in the matter of building construction. Hence, 
permission to erect warehouses and factories in ferro- 
concrete has always been difficult — and often impossi- 
ble — to obtain, though experience has shown that the 
new material is most excellent as a fire-resister. At 
the great Baltimore fire it was found that the concrete 
exposed to the flames was seldom damaged to a greater 
depth than one-half inch, though projecting corners 
suffered somewhat more, being rounded off by the 
flames to a radius of about two inches, pointing to the 
advisability of constructing the concrete with well- 



SOS CEAIEXTS AST) COXCEETES 

rounded comers in tlie first instance. The onlv rea- 
sonable grounds ti '"'Ir'iection t?' rtiv rTO' osed svstem 
of bnilding constriiction are it- 'lci-.^ers irom a struc- 
tural sanitary or fire-risk point of view. A? a res ilt 
of mucli investigation and experiment, tlie tollowing 
conclusions were arrived at for the guidance of the 
designer and constructor of reinforced concrete : 

1. "What drawings and details sli; .;lf_ "_ : prepared 
before work is commenced. 

2. The nature of the materials wMcb may be em- 
ployed and the standards to which these should com- 
ply, i. e.. 

(a^ the metal in reinforcement, 
(h) the matrix, 

(c) the sand. 

(d) the gravel, stone, clinker or other a^regate, 

(e) water. 

3. "What are the proportions for concrete to be used 
ir. din'erent cases. 

4:. How the ingredients for concrete are to be mixed 
and d-posited on the work. 

5. The distances to be allowed between the reinfor- 
cing bars and what covering of concrete is necessary. 

6. "What precautions are necessary in the design and 
erection cf centring and false work, and how long the 
whole or portion of centring and false work sh: vJd re- 
main in position. 

7. The rules which should be used in determining 
the dimensions of the several parts n^:e-s-ary f:r -enir- 
ity, and what safe stresses should ;: - a/ 1. 

8. The supervision necessary and the special matters 
to which it should be directed. 



HOW TO USE THEM 509 

9. The fire-resisting properties of reinforced con- 
crete. 

10. Its adaptability for structures where resistance 
to liquid pressure is essential, and what special precau- 
tions may be advisable under these conditions. 

11. What are the necessary conditions for its perma- 
nence; resistance to rusting of metal, disintegration of 
concrete or effects of vibration. 

12. The testing of the materials employed and of the 
finished structures. 

13. What provisions are desirable in Building Laws 
or Government regulations relating to buildings and 
other structures so far as these affect the use of rein- 
forced concrete. 



CONCRETES, CEMENTS, MORTARS, PLASTERS 

AND STUCCO 

The student will be expected to read carefully these 
papers before doing any work. His name and address 
will be required to be given on each paper. He will 
be expected to write up the questions in a neat and in- 
telligent manner, using his own language and style, rep- 
resenting the answers in such a manner as will be in- 
telligible — make all drawings as clear as possible, and 
wherever it can be done render them in India ink. Let 
each answer be original, do not copy either from the 
instruction papers nor from any other source. The 
paper used may be of any kind provided that it is clean 
and durable. Do not attempt an answer until you have 
thoroughly grasped the subject. 

QUESTIONS 

1. Give a description of the lime principally used for 

internal plastering. 

2. Give a description of those which are known as 

"Hydraulic Limes" and the properties they pos- 
sess. 

3. Give a description of "artificial hydraulic limes" 

and how they may be mixed. 

4. Give a description of the process termed "slak- 

ing" and how to effect it thoroughly, and what 
lime will slake quicker than others. 

510 



QUESTIONS 511 

5. Give a description of how the lime should be 



^'riin/^ 



6. Give a description of the two important purposes 

for which sand is used in the composition of 
plaster. 

7. Give a description of the composition and proper- 

ties of sand for the several purposes for which it 
is best adapted. 

8. Give the general rule for the proportion of sand 

to lime in the composition of plaster. 

9. Give a description of where sand is obtained, and 

what kind should be avoided, and the reason for 
doing so. 

10. Give a description of river sand, its properties, and 

for what class of work it is used. 

11. Give a description of the purpose of hair in the 

composition of plaster, the kind generally used, 
its characteristic qualities, and proper method in 
its manipulation. 

12. Give a description for what purposes Portland Ce- 

ment with a large proportion of sand, may be 
utilized. 

13. Give the designations of the ''setting cements'' 

that are generally the stronger. 

14. Give a description of ''Roman Cement," its 

disadvantages, and its utility for certain pur- 
poses. 

15. Give the names of other "natural cements" very 

similar to Roman, and that are also useful where 
quick setting is required. 

16. Give a description of "Parian Cement," for what 

kind of work it is best adapted, and the qualities 
it possesses. 



512 CEMENTS AND CONCRETES 

17. Give a description of ''Keene's Cement," its dom- 

inant property over other kinds, and the utility 
to which it may be adapted. 

18. Give a description of ''Martin's Cement," the 

properties it possesses, and for what purpose is 
it principally utilized. 

19. Give a description of some of the advantages de- 

rived from the use of "Robinson's Cement." 

20. Give a description of "Adamant," and the proper- 

ties it possesses. 

21. Give a description of "Selenitic Cement," the prop- 

erties it possesses, and its utility. 

22. Give a description of "Plaster of Paris," its pro- 

portion to ordinary lime putty^ and its utility 
for various purposes. 

23. For what purpose are pine, cedar and metal laths 

used ? 

24. Describe the defects that are to be avoided in laths, 

and the reason for their rejection. 

25. Give the description of "Riven Laths." 

26. Give the three sizes in which laths may be obtained, 

and the terms applicable to each respectively. 

27. Give a description where the "thicker" and "thin- 

ner" laths should be used respectively, and the 
reasons why so described. 

28. Give a description of how laths are usually spaced. 

29. Give a description of what is meant by "A Bunch 

of Laths, ' ' what it contains, the number of super- 
ficial yards it will cover, and the number of nails 
required when nailed to joists 1 ft. from center 
to center. 

30. Give a description of the lengths of laths. 



QUESTIONS 513 

31. Give a description of how laths are best nailed so 

as to break joint entirely. 

32. Give a description of how ^'Lap Joints*' at the 

end of laths should be treated. 

33. Give a description of how joists that are thicker 

than 2 inches should be treated. 

34. Give a description of the qualities possessed by 

'* Metal Lathing" and why it is now extensively 
used. 

35. Give a description of the various kinds of ''lath- 

ing nails" and the different purposes for which 
they are used. 

36. Give a description of the purposes for which Port- 

land cement is best adapted, and the qualities it 
possesses. 

37. Give a description of the composition of the cement 

for ''rendering." 

38. Give a description of the plastering operations of 

"External Facades in Portland Cement." 

39. Give a description of how the key for external plas- 

tering on brick work may be obtained. 

40. Should fat lime be mixed with Portland cement? 

41. Give a description of the term "Stucco" and to 

what it is applied. 

42. Give a description of "common stucco," its com- 

position and how employed. 

43. Give a description of "rough stucco," how it is 

utilized and manipulated. 

44. Give a description of "Bastard Stucco and Trow- 

elled Stucco," their composition and purposes for 
which they are adapted and how manipulated. 

45. Give a description of the term "Sgraffito," and 

how patterns may be obtained. 



514 CEMENTS AND CONCRETES 

46. Give a description of "the design for the "Sgraf- 

fito." 

47. Give a description of "rough cast," its composi- 

tion^ qualities, and method of manipulation. 

48. Give a description of "Depeter, " the qualities it 

possesses, and the several methods of manipulat- 
ing it. 

49. Give a description of "Lime plastering," its com- 

position, and manner of its application. 

50. Give a description of what is meant hy "one-coat 

work" in plaster work operations. 

51. Give a description of "two-coat work" in plaster 

work operations. 

52. Give a description of "three-coat work" in plaster 

work operations. 

53. Give a description of the several processes in plas- 

tering ordinary three-coat work. 

54. Give a description of "Gauged stuff," its composi- 

tion, the purposes for which it is used, and man- 
ner of its manipulation. 

55. Give a description of "the white cements," their 

composition, and manner of adaptation. 

56. Give a description of some of the causes that pro- 

duce the cracks often observable in plaster work. 

57. Give a description of how the joist lines on ceilings 

are caused, and how they may be prevented. 

58. Give a description of the process termed "Pug- 

ging," and the purposes for which it is intended. 

59. Give a description of "Mineral Wool," its com- 

parison with ordinary pugging, its qualities, and 
purposes for which it is adapted. 



QUESTIONS 51J 

60. Give a description of ''Lime Whiting or White- 

wash," its composition, and purposes for which 
it is adapted. 

61. Give a description of ''fibrous plaster," its com- 

position, and the adaptability of the qualities it 
possesses. 

62. Give a description of the methods in which orna- 

mental plaster ceilings may be treated. 

63. Give details separately of the 17 rules that are 

embraced under ' ' Specification Clauses ' ' and rela- 
tive to materials and workmanship. 

64. Give a description of the preparation of Bill of 

Quantities. 

65. Give a description of ' ' Laths Generally, ' ' the meth- 

od of manipulating them, and the different kinds 
of nails used. 

66. Give a description of the "Hoes and Drags" used 

by the plasterer, and the purposes for which they 
are utilized. 

67. Give a description of the article known as "The 

Hawk," and for what purpose it is used. 

68. Give a description of the ' ' Mortar Board, ' ' and for 

what purpose it is used. 

69. Give a description of the different kinds of 

' ' Trowels, ' ' and the respective purposes for which 
they are utilized. 

70. Give a description of the different kinds of 

"Floats," and the respective purposes for which 
they are adapted. 

71. Give a description of "Moulds," how they are 

made and for what purposes they are utilized. 

72. Give a description of " Center-MouldSj " and the 

principle upon which they are made. 



516 ce:jexts and concretes 

73. Give a description of the tool termed "The Point- 

er," and for what it is chiefly used. 

74. Give a description of the process termed lime burn- 

ing or calcination. 

^5. Give a description of what is meant by the term 
"Mortar," its composition and the processes 
which are adopted in its manipulation. 

/6. Give a description of what is meant by "the ad- 
hesive strength" of mortar. 

77. Give a description of the causes that operate in 

the "hardening of mortar." 

78. Give a description of some of the qualities pertain- 

ing to "Mastic," and for what purpose is it some- 
times used? 

79. Give a description of the various processes in the 

manipulation of "Mastic." 
SO. Give a description of the composition of "Scotch 
Mastic." 

81. Give a description of the composition of "Common 

Mastic. ' ' 

82. Give a description of the process termed ' ' Scratch- 

ing, ' ' the tool employed and method of manipula- 
tion. 

83. Give a description of the process termed "Render- 

ing," and how it should be properly done. 

84. Give a description of how to manipulate the wall 

and ceiling "screeds." 

85. Give a description of the term "Flanking" and 

the method of performing the operation. 

86. Give a description of the process in "Scouring 

coarse stuff." 

87. Give a description of the process termed "keying" 

in plaster work, and method of manipulation. 



QUESTIONS 517 

88. Give a description of what is termed ''Setting 

Stuff," and method of manipulating it. 

89. Give a description of the term ''Scouring setting 

stuff," and method of manipulation. 

90. Give a description of the processes known as 

"Trowelling and brushing setting stuff." 

91. Give some general remarks on "Setting," and the 

best method of making joints and setting stuff, 
where it is inconvenient to lay and finish the 
whole surface in one operation. 

92. Give a description of "Common Setting" for walls 

and ceilings, and methods of manipulation. 

93. Give a description of the process termed "Skim- 

ming," and method of manipulation. 

94. Give a description of the process termed "Colored 

Setting," its composition, and method of manipu- 
lation. 

95. Give a detailed description of how to set out and 

construct Corinthian Entablature^ including the 
cornice, enrichments, coffers, modillion blocks, 
and paterae. 

96. Give a description of the method of setting out and 

constructing a mould intended for forming the 
moulding and miters in one operation. 

97. Give a description of how the fixing of enrichments 

should be executed, and what has to be avoided 
during the operation. 

98. Give a description of how the mitering of enrich- 

ments is to be performed, and what should be 
done in fixing medallion blocks, dentils or paterae. 

99. Give the description of a column trammel, and the 

method of its manipulation. 



518 CEMENTS AND CONCRETES 

100. Give a description of the method of constructing 

plain diminished columns. 

101. Give a description of how to set out the flutes of 

a diminished column. 

102. Give a description of how to construct diminished 

fluted columns. 

103. Give a description of diminished fluted pilasters, 

and the method that should be adopted in their 
construction. 

104. Give a description of diminished mouldings, and 

the methods that are adopted in their construc- 
tion. 

105. Give a description of the '' diminished rule meth- 

od" for running double diminished mouldings. 

106. Give a description of the "top rule method" of 

running double diminished mouldings. 

107. Give a description of the method of constructing 

the plaster work of cupolas. 

108. Give a description of templates for running ellip- 

tical mouldings, and methods of their manipula- 
tion. 

109. Give a description of the methods adopted in the 

formation of coved ceilings. 

110. Give a description of the methods adopted in the 

formation of circle mouldings on circular sur- 
faces. 

111. Give a description of the formation of niches or 

recesses in walls, and for what purposes they are 
adapted. 

112. Give a description of the process termed "Fresco,'* 

and how the plaster is to be prepared for the re- 
ception of the decorative operations. 



QUESTIONS 519 

113. Give a description of ''Indian Fresco and Marble 

Plaster," the process of its composition and the 
purposes for which it is adapted. 

114. Give a description of "Scagliola," its excellent 

qualities, durability, and the purposes for which 
it is adapted. 

115. Give a description of the colors and quantities that 

are used for the following marbles, respectively, 
namely, Penzance marble, Egyptian Green, Dark 
Porphyry and Green Genoa. 

116. Give a description of the process of the polishing 

of "Scagliola." 

117. Give a description of the process in the manufac- 

ture of ' ' Marezzo, ' ' and the purposes for which it 
is adapted. 

118. Give a description of the method of executing 

granite plaster work, and how it is manipulated 
in its composition. 

119. Give a description of concrete in general and some 

of the uses to which it is applied. 

120. Give a description of what the term "matrix" 

is applied to when considering the qualities of 
any material. 

121. Give a description of what is meant- by the term 

' ' Compound Aggregates, ' ' and explain the differ- 
ence between an inferior and superior aggregate 
by an example. 

122. Give a description of the "Voids in Aggregates," 

and what method is used to ascertain the voids. 

123. Give a description of the "crushing strength of con- 

crete" and upon what it depends. 

124. Give a description of the "ramming of concrete" 

and the effect that is produced. 



520 ■ CEMENTS AND CONCRETES 

125. Give a description of the thickness of concrete 
paving and its relation to the foundations, and to 
the amount of traffic on street sidewalks, stable 
floors and yards. 

126. Give a description of ''Eureka Paving," its manip- 

ulation, and the purposes for which it is best 
adapted. 

127. Give a description of the method of preparing the 

aggregate for Eureka, and the quantities for the 
rough coat and topping. 

128. Give a description of the ''levelling and adjust- 

ment of the requisite falls ' ' in the laying of con- 
crete pavements and flooring. 

129. Give a description of the two parts in the composi- 

tion of foundations, and the method of manipula- 
tion. 

130. Give a description of the "laying concrete pave-a 

ments ' ' and the processes to be employed in order 
to leave the surface uniform, straight and solid. 

131. Give a description of "trowelling concrete" and 

how the best effects may be attained. 

132. Give a description of the process ^termed ' ' grout- 

ing," and when it is adopted. 

133. Give a description of the methods of composition 

of materials that are sometimes adopted for "non- 
slippery pavements." 

134. Give a description of the preparation of "grooved 

and roughened surfaces," that are required for 
stables, yardSj etc. 

135. Give a description of the process employed in col- 

oring cement work, and how the best results may 
be obtained, also some of the materials to be used 
in producing the color desired. 



QUESTIONS 521 

136. Give a description of the method of depositing con- 

crete, and what should be avoided in the process. 

137. Give a description of the process termed ^'Retem- 

pering, " and the conditions upon which the prop- 
er setting of concrete depends. 

138. Give a description of how to treat operations in 

concrete during freezing weather. 

139. Give a description of ''Rubble Concrete," its com- 

position and method of manipulation. 

140. Give a description of how to face concrete, the 

composition employed, and how it is prepared. 

141. Give a description of the "top dressing or wearing 

surface" for finished walks, and the method of 
mixing the mortar. 

142. Give a description of the composition of ''Base- 

ment Floors" and the method of their treatment. 

143. Give a description of the construction of concrete 

stable floors and driveways. 

144. Give a description of concrete steps, their manner 

of construction, and in what places they may be 
advantageously adopted. 

145. Give a detailed description of wood framing in 

the construction of concrete stairs. 

146. Give a description of the materials required for a 

concrete staircase, and how to manipulate them 
for the several purposes required. 

147. Give a description of "Modelling in Fine Con- 

crete" and the several stages in the development 
of the process to obtain the proper execution of 
the figure or design required. 

148. Give a description of how concrete fountains are 

constructed, and how a saving of material may 
be effected. 



522 CEMENTS AND CONCRETES 

149. Give a description of the construction of concrete 

tanks, and the manipulation of the materials for 
the purposes desired. 

150. Give a description of the composition of ** concrete 

vases/' and the method of manipulating the ma- 
terials. 



INDEX 



PA08 

MATERIALS: 

Limes 2 i 

Cements 30 

Mortars 28 

Sand 28 

Plasters and laths 31 

WORKMANSHIP : 

External work 35 

Internal work 37 

SPECIFICATION CLAUSES: 

Materials 42 

Workmanship 43 

PREPARATION OF BILL OF QUANTITIES: 

Materials 46 

Workmanship 46 

Laths 48 

TOOLS AND APPLIANCES : 

Hoes and drags 50 

The hawk 52 

The mortar board 52 

Trowels 52 

Floats 52 

Moulds 54 

The pointer 54 

The paddle 55 

Stopping and picking out tools 55 

Mitering rod 55 

Scratcher 55 



INDEX 

PAaa 
TOOLS AND APPLIANCES.— Continued. 

Hod 55 

Sieve 56 

Sand screens 56 

Mortar beds 57 

Slack box ; 57 

Lathing 57 

Lather 's hatchet 58 

Nail pocket 58 

Cut-off saw 58 

PLASTER, LIME, CEMENTS, SAND, ETC. : 

Plaster of Paris 60 

Quick and slow setting plaster 62 

Testing 63 

French plaster 65 

Limes 65 

Hydraulic limes ^^ 

Calcination 69 

Slaking 70 

Mortar 73 

Hardening of mortar 78 

Magnesia in mortars 82 

Effects of salt and frost in mortar 84 

Sugar with cement 86 

Sugar in mortar 88 

Lime putty 89 

Setting stuff 90 

Haired putty setting 91 

Lime water 91 

Hair 91 

Fibrous substitutes for hair 92 

Sawdust as a substitute for hair 93 

Sand 94 

Mastic 96 

Scotch mastic 96 

Common mastic .'. 97 

Mastic manipulation 97 



INDEX 

PAGE 

PLASTER, LIME, CEMENT, ETC.— Continued. 

Hamelein 's mastic 97 

Mastic cement 98 

TERMS AND PROCESSES : 

Three-coat work 99 

First coating 99 

Scratching 100 

Rendering 102 

Screeds 103 

Floating 103 

Flanking 106 

Scouring coarse stuff Ill 

Keying 112 

Setting 114 

Laying setting stuff 115 

Scouring setting stuff 115 

Troweling and brushing setting stuff 116 

General remarks on setting 117 

Common setting 119 

Skimming . 119 

Colored setting 119 

Gauged setting 120 

Gaue^ed putty set 120 

Putty set 121 

Internal angles 121 

External angles 121 

Skirtings 122 

Two coat work 123 

One-and-a-half coat work 123 

Stucco 124 

Old stucco 124 

Common stucco 129 

Rough stucco 129 

Bastard stucco 130 

Troweled stucco 130 

Colored stucco 131 

Method of working cements 131 



INDEX 

PAGE 

TERMS AND PROCESSES.— Continued. 

White cement efflorescence 138 

Cornice brackets 139 

Cornices 140 

Mitring 155 

Mitre mould 156 

Fixing enrichments 159 

Mitring enrichments 160 

Pugging 163 

Sound ceilings 164 

Cracked plaster work 165 

Repairing old plaster 165 

Gauged work 168 

Joist lines on ceilings 169 

Rough casting 170 

VARIOUS METHODS OF RUNNING COR- 
NICES, CIRCLES, ELLIPSES AND OTHER 

ORNAMENTAL STUCCO WORK: 

Diminished columns 177 

Column trammel 180 

Constructing plain diminished columns 183 

To set out the flutes of diminished columns .... 183 

Constructing diminished fluted columns 185 

Forming diminished fluted column by the rim 

method 193 

Running diminished fluted column by the Col- 
lar method 196 

Diminished fluted pilasters 200 

Pannelled coves 200 

Diminished mouldings 204 

False screed method 204 

Running double diminished mouldings 208 

Diminished rule method 208 

Top rule method 211 

Cupola panels and mouldings 215 

Panelled beams 220 



INDEX 

PAGE 

VARIOUS METHODS, ETC.— Continued. 

Trammels for elliptical mouldings 220 

Templates for elliptical mouldings 224 

Plasterer 's oval 228 

Coved ceilings 233 

Circle mouldings on circular surfaces 233 

Forming niches 235 

Running an elliptical moulding in situ 240 

MISCELLANEOUS MATTERS: 

Depeter 243 

Sgraffitto 243 

Fresco 251 

Fresco secco 255 

Indian fresco and marble plaster 256 

Scagliolia 260 

Artificial marbles 262 

Pick 's neoplaster 263 

Scagliolia manufacture 264 

Mixing 270 

Colors and quantities 272 

Polishing white scagliolia ' 275 

Polishing scagliolia 276 

Marezzo 277 

Granite finish 282 

Granite plastering 283 

CEMENTS AND CONCRETES AND HOW TO 

USE THEM: 

Fine concrete 291 

Matrix 293 

Aggregate 294 

Porous aggregates 295 

Compound aggregates 296 

Sand and cement 297 

Fire-proof aggregates 300 

Voids in aggregates 302 

Crushing strength of concrete 302 



INDEX 

PAGE 

CEMENTS AND CONCRETES.— Continued. 

Water for concrete 303 

Gauging concrete 305 

Ramming concrete 308 

Thickness of concrete paving 309 

Concrete paving 310 

Eureka paving 312 

Eureka aggregate 313 

Eureka quantities 314 

Levels and falls 315 

Pavement foimdations 316 

Screeds and sections 318 

Laying concrete pavements 320 

Troweling concrete 321 

Grouting 322 

Dusting 322 

Temperature 322 

Non-slippery pavements 323 

Grooves and rougiiened surfaces 323 

Stamped concrete 325 

Expansion joints 325 

Washing vards 328 

Stable pavements 328 

Concrete slab moulds 329 

Slab making 330 

Induration concrete slabs 330 

Mosaic 331 

Concrete mosaic 333 

Concrete mosaic laid in situ 334 

Storing cement 337 

Cement mortar 337 

Mixing 338 

Grout 339 

Lime and cement mortar 339 

Cement mortar for plastering 339 

Materials for making concrete sand 340 

Gravel 341 



INDEX 

PAGE 

CEMENTS AND CONCRETES.— Continued. 

Crushed stone 341 

Stone versus gravel .' 342 

Cinders 342 

Concrete 343 

Proportioning materials 344 

Aggregate containing fine material 345 

Mechanical mixers 346 

Mixing by hand 346 

Consistency of concrete 347 

Use of quick setting cement 347 

Coloring cement work 347 

Depositing concrete 348 

Retempering 349 

Concrete exposed to sea-water 349 

Concrete work in freezing weather 350 

Rubble concrete 350 

To face concrete 351 

"Wood for forms 352 

Concrete sidewalks 352 

Excavation and preparation of subgrade 353 

The subfoundation 353 

The foundation 353 

The top dressing or wearing surface 354 

Details of construction 384 

Concrete basement floors 358 

Concrete stable floors and driveways 358 

Concrete steps 359 

Reinforced concrete fence posts 360 

Reinforcement 362 

Concrete for fence posts 362 

Molds for fence posts 363 

Attaching fence wire to posts 365 

Molding and curing posts 365 

Concrete building blocks 368 

Tests of concrete fence posts. . . . . .-, 370 

Retempering 378 



INDEX 

CEMENTS AND CONCRETES.— Continued. 

Some practical notes 380 

Concrete stairway and steps 387 

Cast concrete stairs 389 

Test of steps 390 

Concrete stairs formed in situ 391 

Setting out old stairs 391 

Nosings and risers 392 

Framing staircases 394 

Centring for landings and soffits 396 

Waterproof centring 397 

Staircase materials 399 

Filling in stairs \ 400 

Finishing stairs 404 

Non-slippery steps 405 

Striking centrings 405 

Concrete and iron 406 

Setting concrete soffits 408 

Fibrous concrete 408 

Polished soffits '409 

Concrete staircases and fibrous plaster 410 

Dowel holes 410 

Cast steps 411 

Treads and risers 412 

Closed outer strings 413 

Concrete floors 413 

Plaster floors 415 

Joist concrete floors 416 

Caminus concrete cement 417 

Concrete floors and coffered ceilings 418 

Combined concrete floors and panelled ceilings. 419 

Concrete and wood 420 

Concrete drying 421 

Concrete slab floors 423 

Construction of slab floors 425 

Hollow floors 427 

Concrete roofs 428 



INDEX 

PAGE 

CEMENTS AND CONCRETES.— Continued. 

Notes on concrete 429 

Cast concrete 431 

Concrete dressing 432 

Mouldings cast in situ 438 

Modelling in fine concrete. 443 

Concrete fountains 446 

Concrete tanks 446 

Concrete sinks 448 

Garden edging 448 

Concrete vases 448 

Concrete mantel pieces 449 

Colored concrete . 449 

Fixing blocks 452 

Typical system of reinforced concrete construc- 
tions from various sources 452 

Columns and piles 458 

Floors, slabs and roofs 468 

Beams 469 

Arches „ 471 

Lintels 473 

Concrete walls 475 

Strong rooms 475 

Concrete coffins and cementation 475 

Tile fixing . 477 

Setting floor and wall file 479 

Foundations 479 

Lime mortar 480 

Concrete 480 

For floors -. . 480 

For wood floors 480 

In old buildings. 481 

For hearths 482 

For walls 484 

Cement 486 

Sand 486 

Mortar 486 



INDEX 

PAGE 

CEMENTS AND CONCRETES.— Continued. 

Soaking 486 

Tiles for floors 486 

Ceramics 488 

Files for walls and wainscoting. 490 

Floating wall tile 491 

Buttering ^all tiles 491 

Hearth and facing tile 492 

Cleanino; 492 

Cutting' of tile 492 

Tools 492 

Laying tile on wood 493 

Good concrete 495 

Eeinf orced concrete 500 



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Farm Engines and How to Run Them — 

Stephenson. Illustrated 1.00 ... 

Furniture Making, Home — Raeth. Illus- 
trated 60 ... 

First Steps in Electricity, or Electricity 

for Beginners — Harrison 1.00 . . . 

Gas and Oil Engine Hand Book- 
Brookes. Illustrated 1.00 1.50 

Hand Book for Engineers and Electri- 
cians — Swingle. Illustrated. Pocket 
Book Style S.OO 

Hardwood Finishing, Up-to-date — Hodg- 
son. Illustrated l.OO ... 

Horse Shoeing, Correct — Holmstrom. Il- 
lustrated 1.00 ..i 

Hot Water Heating, Steam and Gas Fit- 
ting — Donaldson. Illustrated 1.50 

Heating and Lighting Railway Passen- 
ger Cars — Prior 1.25 

Locomotive Breakdowns, with Questions 

and Answers — Wallace. Illustrated 1.50 

Locomotive Fireman's Boiler Instructor — 

Swingle 1.50 

Locomotive Engineering — Swingle. Illus- 
trated. Pocket Book Style 3.00 

Machine Shop Practice — Brookes. Illus- 
trated 2.00 

Mechanical Drawing and Machine Design 

— ^Westinghouse. Illustrated 2.00 

Motorman, How to Become a Successful. 

Aylmer-Small. Illustrated 1.50 

Motorman's Practical Air Brake Instruc- 
tor — Denehie 1.50 

Modern Electric Illumination, Theory 
and Practice — Horstmann & Tousley. 
Illustrated 2.00 

Millwright's Practical Hand Book — SwIjj- 

gle. Illustrated i.OO ... 

Modern American Telephony In All Its 
Branches — Smith. Illustrated 2.00 



• • • 



• • 



• • ' 



• • • 



I*rlc6, 
Titles. Cloth. Lea, 

Operation of Trains and Station Work — 
Prior. Illustrated 1.60 

Painting', Cyclopedia of — Maire. Illus- 
trated 1.50 ... 

Pattern Making and Foundry Practice — 
Hand. Illustrated 1.50 

Picture Making for Pleasure and Profit — 

Baldwin. Illustrated 1.25 ... 

Plumbing, Practical, Up-to-Date — Clow. 

Illustrated 1.50 . . . 

Railway Roadbed and Track, Construc- 
tion and Maintenance of — Prior. Illus- 
trated 2.00 

Railway Shop Up-to-Date — Haig. Illus- 
trated 2.00 

Sheet Metal Workers' Instructor — Rose. 

Illustrated 2.00 

Slgnist's Book of Modern Alphabets — Del- 

amotte 1.50 

Sign Painting, The Art of — Atkinson... 3.00 

Stair Building and Hand Railing — Hodg- 
son. Illustrated 1.00 

Steam Boilers — Swingle. Illustrated : 

Steel Square, A Key to — Woods. 1.50 

Steel Square, Vol. I— Hodgson. Illus- 
trated 1.00 

Steel Square, Vol. II — Hodgson. Illus- 
trated 1.00 

Steel Square, A B C — Hodgson 50 

Steel Construction, Practical — Hodgson. 

Illustrated 50 

Storage Batteries — Niblett 50 

Sho' Cards, A Show At — Atkinson and 

Atkinson 3.00 

Stonemasonry, Practical, Self-Taught — 

Hodgson. Illustrated 1.00 

Telegraphy Salf-Taught — Edison. Illus- 
trated 1.00 

Telephone Hand-Book — Baldwin. Illus- 
trated 1.00 

Timber Framing, Light and Heavy — 
Hodgson 2.00 

Toolsmith and Steel Worker — Holford. 

Illustrated 1.50 

Turbine, The Steam — Swingle. Illustrated 1.00 

Walschaert Valve Gear Breakdowns and 
How to Adjust Them — Swingle. Illus- 
trated 1.00 

Wiring Diagrams, Modern — Horstmann 

& Tousley. Illustrated 

Wireless Telegraphy and Telephony — 

V. H. Laughter 1.00 

Wood Carving, Practical — Hodgson. Illus- 
trated 1.50 

THE BED BOOK SEBIES OF TBADE SCHOOL 

MANUALS 
By F. Maire 

16 mo., Cloth, Illustrated. Price, each, ?0.60 

Exterior Painting, Wood, Iron and Brick. 
Interior Painting, Water and Oil Colors. 
Colors, What They Are and Whai to Expect 

from Them. 

Graining and Marbling. 
Carriage Painting. 
The Wood Finisher. 



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